Beginner Seasoned
Pick your zone and the dates re-calibrate.
The Guide Fruit trees Vol. 004

Orange (Navel)

in Zone 9, this week

The navel orange is an evergreen citrus tree that makes seedless, easy-to-peel oranges. The catch with navels is heat: unlike lemons, which make good fruit in lots of climates, navel oranges need a lot of summer heat to turn sweet and orange. In cool coastal areas the tree grows fine and even makes fruit, but the fruit can stay sour and pale because there is not enough heat to make it sweet. In hot inland valleys and the desert, those same trees make deeply colored, sweet fruit. So two things shape where navels do well: cold limits how far north they grow, and summer heat decides whether the fruit gets sweet. One tree makes fruit on its own, with no second tree needed. The navel orange (Citrus sinensis) is a subtropical evergreen fruit tree prized for its seedless, easy-to-peel fruit. Unlike lemons, which produce quality fruit across a wide range of climates, navel oranges require substantial accumulated summer heat to develop full sweetness and color. In cool coastal areas, navel fruit often remains acidic and pale even though the tree is healthy and frost-safe, because heat is insufficient for sugar development. In warm inland valleys and desert regions, the same varieties produce deeply colored, sugar-rich fruit. This dual gating, cold limiting where the tree survives and heat limiting where it produces quality fruit, is the defining regional story for navel oranges. Trees are grafted onto rootstock selected for disease resistance, cold tolerance, and soil adaptability. A single tree can remain productive for 50 years or more with proper care.

Orange (Navel) mature plant
Fig. 01 · Orange (Navel), mature Zone 9
First fruit
3-4 yrs
to first harvest
Sunlight
Full sun
8-12 hrs daily
Water
Moderate
Spacing
15 to 20 ft
between trees
Soil pH
6-7
slightly acidic
Hardiness & fruiting range

Will it actually fruit here?

Hardiness tells you the tree will survive your winters. It does not tell you whether you will get fruit. Each zone carries its own verdict. Yours is marked.

3
survives,
rarely fruits
4
survives,
rarely fruits
5
survives,
rarely fruits
6
survives,
rarely fruits
7
survives,
rarely fruits
8
survives,
rarely fruits
Your zone
9
reliable
10
reliable
11
reliable
Fruits reliably
Fruits reliably Survives only Too warm
← colder winterswarmer, less chill →
✓ Zone 9: Zone 9 in the valley is ideal for oranges. Hot summers make the fruit sweet and deeply colored, and winters are usually mild enough to keep the crop.Zone 9 valley floor is the navel sweet spot: high summer heat for full sugar and color, and winter lows that only occasionally threaten the crop. This is the climate that built California's navel industry.
The growing year

Your orange (navel) year, month by month

California: Interior, Zone 9. Zone 9 in the valley is ideal for oranges. Hot summers make the fruit sweet and deeply colored, and winters are usually mild enough to keep the crop.Zone 9 valley floor is the navel sweet spot: high summer heat for full sugar and color, and winter lows that only occasionally threaten the crop. This is the climate that built California's navel industry.

A fruit tree runs on the same rhythm every year: rest, prune, bloom, grow, harvest, then settle in again.

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
▲ We are here
Tree’s year
harvest
bloom
growing
harvest
Dormant rest Prune Bloom Growing fruit Harvest Post-harvest care
Plant bare-root
Spring; much of the year on the mild valley floor
Bloom
Apr - May
Harvest
Dec - Apr (late selections such as Lane Late hold into spring)
Chill hours

Will your winter be cold enough?

Oranges do not need any winter chill to flower or fruit. Unlike peaches and apples, which need hundreds of cold hours in winter to wake up and set a crop, citrus is evergreen and is triggered to bloom by spring warmth and moisture instead. So chill hours, which matter a lot for deciduous fruit trees, simply do not apply to oranges.Navel oranges require no chilling to flower or fruit. They are evergreen and do not enter a physiological dormancy triggered by chill accumulation. Flowering is driven by spring warming and moisture rather than release from a prior cold period. This distinguishes citrus from deciduous fruit trees such as peaches and apples, which require hundreds of chill hours to break bud dormancy and set a normal crop.

✓Dependable here
Washington0Cara Cara0Lane Late0Fukumoto0
!Borderline in a warm winter
None. Every variety in this roster gets enough chill here.
Bloom timing & cross-pollination

One tree is usually enough

Most orange (navel)s are self-fruitful: a single tree sets a full crop with its own pollen, so you don’t need a second variety to get fruit. Bees still move the pollen from blossom to blossom, so strong pollinator activity through bloom is what drives a heavy set.

Washington blooms mid season and is self-fruitful, setting a full crop on its own.Blooms alongside: Cara Cara, Lane Late, Fukumoto.

Bar length shows how long each variety blooms, roughly 8 to 14 days. Bars that overlap bloom at the same time.

▲ Tap a variety to see its bloom timing

Very early Early Mid Late Very late
Washington✓ same time
Cara Cara✓ same time
Lane Late✓ same time
Fukumoto✓ same time
The pollination rule

A navel orange makes fruit all by itself, with no second tree and no bees needed. It does this through a natural process that swells the fruit without pollination, which is also why the fruit is seedless. In fact, if pollen from another nearby citrus does reach the flowers, it can put seeds into the fruit, so keeping a navel away from other pollen-making citrus actually helps keep it seedless.Navel oranges are parthenocarpic and male sterile, producing seedless fruit without pollination. The fruit develops through a hormonal process that swells the ovary independently of fertilization. Because navels produce no viable pollen, a single tree will set a full crop on its own. Cross-pollination from nearby citrus varieties with fertile pollen can actually introduce seeds into the fruit, so isolation from pollen-bearing citrus preserves the seedless quality that defines the navel type.

Pick your variety

Recommended varieties

All navel oranges make seedless, easy-to-peel fruit and need a lot of summer heat to get sweet. Washington is the classic all-purpose navel. Cara Cara is a navel with pink-red flesh and a sweeter, berry-like taste. Lane Late ripens later and holds on the tree longest, stretching your season. Fukumoto colors up early. Pick based on when you want fruit and whether you would enjoy the pink-fleshed Cara Cara.All navel oranges are clonal bud sports or mutations tracing back to the original Washington navel, which was introduced to the United States from Bahia, Brazil in the 1870s. Variety differences are primarily in maturity timing, rind color development, and flesh pigmentation rather than tree habit or hardiness. All are seedless and parthenocarpic. In regions with marginal heat, early-coloring selections like Fukumoto may reach acceptable sugar levels sooner. Late selections like Lane Late extend the harvest window without requiring a second tree.

Washington
fresh eating, juice
Cara Cara
fresh eating
Lane Late
fresh eating, juice
Fukumoto
fresh eating
Rootstock & size

How big will it get?

Carrizo citrange is the most widely used rootstock for sweet oranges. It provides good disease resistance and fruit quality. For containers or small spaces, Flying Dragon trifoliate produces a compact tree. Ask the nursery which rootstock the tree is grafted onto and match it to your soil and space.

Recommended
Carrizo citrangestandard
Mature height
15 to 25 ft
Bears
year 3
Container
in-ground
Swingle citrumelostandard
Mature height
12 to 20 ft
Bears
year 3
Container
in-ground
Flying Dragon trifoliatedwarf
Mature height
5 to 8 ft
Bears
year 3
Container
pot OK
Ask the nursery

Ask for a certified disease-free tree on Carrizo citrange. Confirm your soil is not highly alkaline or saline, as Carrizo is sensitive to both conditions.

From seed to fruit

The growing journey

Stage 01 · Planting and settling in
01
Planting and settling in
Over the next few weeks you should see new leaves pushing out. Check that the soil has not settled up and over the graft union.Expect roots to begin working and a first push of new leaves over the coming weeks once the soil warms, with the canopy staying firm instead of drooping. Keep an eye on the mound as it settles so the graft union does not end up buried.
Plant the tree slightly raised on a low mound, with the knobby graft union sitting above the soil. Soak it in well after planting and keep mulch off the trunk. If you have heavy clay, build the mound a little higher so the water drains.Set the tree high on a mound so the graft union clears the soil and mulch line, fill back around the roots with the native soil, and water it in to settle the air pockets, keeping mulch off the trunk. Pull off the nursery wrap, and add a stake only if the tree needs the support. Where the ground is clay, build the mound up more, since fast drainage is the navel's first requirement.
FROM PLANT · Plant so the graft bump sits a couple inches above the soil, and keep mulch off the trunk. A buried, damp union can rot.Plant with the graft union standing two to three inches clear of the finished soil and keep mulch pulled back from the trunk. A buried or mulch-packed union stays damp and is the classic entry point for foot rot in citrus.
FROM PLANT · Soak the tree right after planting so the soil settles, then wait until you see new leaves before fertilizing.Water in well to settle the soil, then wait for new growth before the first feeding. Fertilizer applied before the roots are active simply leaches past them, and on a young tree that is wasted nitrogen and a salt risk.
02
Establishment years
You want to see the tree getting bigger each year, with new branches and a fuller canopy. Do not worry that there is little or no fruit yet, that is exactly what should happen.Steady extension of new shoots and a filling canopy each warm season. The trunk should thicken and the scaffold branches develop. Little to no fruit is the goal here, not a worry.
For the first couple of years, focus on growing a strong tree rather than getting fruit. Pinch off the flowers the first year so the tree builds roots instead. Water it regularly, feed it, and protect it from frost in winter, since young trees are more cold-tender than older ones.Build the tree, not the crop. Remove flowers and any fruit set in the first year (and consider thinning hard in the second) so energy goes to roots and framework. Water consistently to establish the root system, feed on the citrus nitrogen rhythm, and protect young, frost-tender wood through its first winters. In extreme-heat climates, shield the young trunk from sunburn.
FROM PLANT · For the first two years or so, pick off the fruit. Navel oranges take almost a year to ripen, which is a big load, so let the young tree grow strong first.Strip the first couple of years' fruit so the tree builds frame before it bears. Navels carry a long ten-to-twelve-month crop, which is a heavy draw, and a young tree allowed to hold that load early grows slowly and stays structurally weak.
FROM PLANT · Check the new growth for tiny citrus psyllid insects while the tree is small. They spread a serious citrus disease and they go after fresh new leaves, so look them over often.Scout new flush for Asian citrus psyllid while the tree is small and easy to inspect. The psyllid spreads huanglongbing, the disease behind citrus decline, and tender new growth is exactly where it feeds and lays, so catching it early on a young tree matters most.
03
Spring bloom
Sweet-smelling white flowers will open over a few weeks. A navel does not need a second tree or bees to make fruit. Some flowers and tiny fruit will drop on their own, which is normal.Fragrant white blossoms opening over a few weeks. Navels are parthenocarpic, so a single tree sets fruit without pollination; some natural flower and early-fruit drop is normal self-thinning.
When the tree blooms in spring, keep the watering even (not too dry, not soggy) and keep feeding, because this is when it sets the fruit you will harvest next winter. Do not spray oil while it is flowering. If a heat wave hits during bloom, extra water and a little shade help keep the flowers on.Bloom is when the navel is setting its fruit for next winter's harvest, so any stress at this stage costs the coming crop. Keep the root zone evenly moist throughout the bloom period, avoid fertilizer gaps that would slow the tree, and do not let the soil swing dry or become saturated, either of which can trigger flower drop. Hold off on oil sprays while blooms are open to protect pollinators, and in climates where spring heat arrives early, watch for heat spikes that push day temperatures above 95°F during flowering.
FROM PLANT · Keep the soil evenly moist during the few weeks the tree flowers in spring. If it dries out, the flowers and tiny fruit drop, and that spring bloom is the whole year's crop.Hold soil moisture steady through the roughly three-week spring bloom; drought stress now drops flowers and the young fruit behind them. Navels set their whole crop from this one main flush, so protecting it pays off all season.
FROM PLANT · Do not do big pruning while the tree is flowering or right after. Navel oranges pollinate themselves, so just leave the flowers and new fruit alone.Skip heavy pruning during bloom and just after set. Navels are self-fruitful and need no pollination partner, so the job now is simply to leave the flowering wood and developing fruit undisturbed.
04
Fruit set and the long summer hang
The fruit gets bigger through summer and fall, and the skin starts to color up as cooler weather comes (in warm-enough climates). Keep an eye on fruit on the sunny side during heat waves, and on any fruit dropping.Fruit expanding through summer and into fall, with rind color developing as cooler weather arrives in heat-adequate climates. Watch for sun-exposed fruit on the hot side of the canopy and for drop during heat spikes.
Over the summer the fruit grows slowly and the tree's sugar builds up with the heat. Keep watering steadily, and water extra during heat waves so the fruit does not drop or get sunburned. The amount of summer heat is what makes a navel sweet: in hot inland and desert areas it sweetens fully, but in cool coastal areas the fruit may stay sour no matter what you do.This is where the heat axis decides the crop. Keep irrigation steady through fruit sizing, increasing it during extreme-heat spells to prevent fruit drop and rind sunburn. The accumulated summer heat over these months drives sugar and color development: in hot interior and desert climates the fruit sweetens fully, while in cool coastal climates the tree carries fruit that may never fully sweeten regardless of care.
FROM PLANT · Keep watering deeply and evenly all summer. Navel oranges take many months to grow, and uneven watering makes them split or drop, so stay consistent.Water deeply and consistently across the long summer hang. The fruit develops over ten to twelve months, and uneven moisture during that stretch shows up later as splitting and pre-harvest drop, so a steady irrigation rhythm through summer heat is the priority.
FROM PLANT · If the tree drops a lot of small fruit a few weeks after flowering, that is normal. It is just keeping the fruit it can ripen well, so do not panic.Treat the natural drop a few weeks after set as the tree self-thinning, not a problem. It is shedding more fruit than it can finish, and the fruit that stays will size up better for it, so do not react by overwatering or overfeeding.
05
Winter ripening and harvest
In warm-enough areas the fruit turns full orange, comes off the stem easily, and tastes sweet. In cool coastal areas it reaches this point but may still taste sour, which is the main limitation of growing navels there.Full color in heat-adequate climates, easy separation from the stem, and sweet, low-acid flavor on tasting. In cool-coast climates the same window arrives but fruit may remain tart, the defining limitation of the site.
Pick by taste, not just by color. Navels turn orange as the nights get cold, but in mild or humid areas the skin can still look a little green even when the fruit is ripe, so taste one first. Once ripe, navel oranges hold beautifully on the tree and you can harvest over a stretch of two to three months rather than all at once; they often get sweeter the longer they stay on, so there is no rush.Harvest by taste, not color alone. Navels color up as nights cool, but in mild or humid climates the rind can stay green-tinged on fully ripe fruit, so taste-test before deciding. Fruit holds and continues to sweeten on the tree for weeks to months, which makes timing forgiving; pick over an extended window rather than all at once. Late varieties such as Lane Late stretch the harvest furthest.
FROM PLANT · Taste a navel before picking the whole tree. They turn orange before they are sweet, so try one first instead of judging by color.Taste before you strip the tree. Navels color up before they are fully sweet, and rind color in mild-winter areas is a poor maturity guide, so sample a fruit from the sunny side first and let flavor, not the orange skin, call harvest.
FROM PLANT · You can leave ripe navels on the tree and pick them over several weeks. They keep well on the branch, so there is no rush to pick them all at once.Leave ripe navels on the tree and pick over a long window rather than all at once. The fruit holds well on the branch for weeks, though quality eventually softens, so pull what you need and let the rest keep storing themselves outdoors.
06
Mature bearing
Steady crops each year (some years a bit heavier than others is normal). Watch for shoots sprouting below the graft knob, and for any general decline that could mean a drainage or root problem.Consistent annual crops, with mild natural alternate-bearing tendencies. Watch for rootstock suckers below the graft, declining vigor that signals a drainage or root issue, and the heat-driven quality that defines each site's fruit.
Once the tree is grown up, it settles into a yearly routine: water deeply but not too often (more in heat), feed it through spring and summer and stop by late summer, and do a little light pruning in spring after you harvest. Remove any shoots coming from below the graft knob, since those are from the rootstock and will not make navels. A healthy navel tree produces for many years.Settle into the annual rhythm: deep, infrequent irrigation adjusted up in heat; nitrogen-forward feeding spring through summer, stopping by late summer; light shaping in spring after harvest plus removal of any below-graft rootstock shoots. A mature navel is long-lived and productive for decades on good drainage, and the long on-tree hold lets you harvest across months.
FROM PLANT · On a grown tree, prune lightly. Take out dead wood and any shoots from below the graft bump, since those come from the rootstock and not your orange variety.Keep pruning minimal on a bearing navel: deadwood, crossing limbs, and rootstock suckers from below the graft. Those suckers are the rootstock, not your navel, and left to grow they sap vigor and can overrun the productive top.
FROM PLANT · Navel trees often make a big crop one year and a small one the next, which is normal. Steady feeding and watering helps even it out, but a sudden big drop means something is wrong to check.Expect alternate bearing and feed and water to even it out. Navels naturally swing between heavy and light crop years, and steady fertility plus consistent irrigation softens the swing, while a sharp unexplained drop instead points to a root, water, or disease problem worth chasing down.
The specs

Care guide

The numbers that matter, at a glance.

Sunlight
Full sun · 8-12 hrs/day
Water
moderate
Spacing
15 to 20 feet
Soil pH
6 to 7
Container OK?
Yes
In a pot

Yes, on a dwarf rootstock

A dwarf orange on Flying Dragon rootstock does well in a big pot. That is exactly why a pot is the trick for cold climates: you can move it under cover when frost comes. Use a big pot (bigger is better for a fruiting tree) with plenty of drainage holes and a loose citrus mix, and plan to water and feed more often than a tree in the ground.A navel on Flying Dragon (a naturally dwarfing trifoliate rootstock) is well suited to a large pot. This makes the navel the cold-climate frost-escape play: a pot you can move under cover. Choose a large container (the bigger the better for a fruiting tree), ensure ample drainage holes, use a coarse citrus mix, and expect to water and feed more often than an in-ground tree.

Watering
Pots dry out much faster than the ground, especially in heat and wind, so check a potted orange often, maybe every day in summer. Water until it drips out the bottom, then let the top inch dry before watering again. Do not let the pot sit in a saucer full of water.Container trees dry out much faster than in-ground ones, particularly in the summer heat that navels need for sweetness. Check the pot daily in hot or windy periods and water before the root zone dries out completely. Good drainage is critical: the saucer should stay empty, not pooling water against the roots. The combination of frequent, deep waterings and a fast-draining mix is what keeps a potted navel healthy.
Self-watering pot
Self-watering containers are risky for citrus and generally not recommended, because their constantly moist reservoir works against the soak-and-dry cycle citrus needs and raises the foot-rot risk. If used at all, choose one with a true overflow and a coarse mix, let the reservoir empty between fills, and watch closely for overwatering signs.
Mix
Sharp drainage inside the pot is the priority. A mix sold specifically for citrus or cactus works well; so does a quality potting mix lightened with extra perlite or coarse pine bark to keep it from compacting. Never use straight garden soil in a container because it packs tight and holds moisture against the roots. Blend in perlite, pumice, or coarse bark to sharpen drainage further. The goal is a mix that drains freely after watering and never stays saturated, since a potted citrus is even less forgiving of wet feet than one in the ground.
Feeding
Feed more frequently than an in-ground tree at a lighter rate, using a micronutrient-inclusive citrus fertilizer, since pot leaching depletes nutrients and brings on chlorosis quickly.
One to plant on

Flying Dragon trifoliateFlying Dragon is a special dwarfing rootstock that keeps the tree small, which makes it perfect for pots and small yards, and it is the key to growing oranges in cold climates since you can move the pot under cover for winter. It also has the best cold hardiness of the common citrus rootstocks and strongly resists root rot. The tradeoff is simply a smaller tree with a smaller crop, which is usually exactly what a container or small-space grower wants.A naturally dwarfing mutation of Poncirus trifoliata that produces very compact trees well suited to containers and small home gardens. Offers the best cold hardiness of any widely available citrus rootstock. Excellent resistance to Phytophthora, citrus nematode, and tristeza virus. Sensitive to high-pH and saline soils. Fruit quality is good and trees are precocious, though total yield per tree is lower due to small canopy size.

Winter

If your winters are cold, growing an orange in a pot is the way to do it: keep it on a small (dwarf) tree and move the pot into a garage, sunroom, or by a bright window indoors when frost is coming, then put it back outside when it warms up. This is how people grow oranges in cold places. While it is inside for winter, water it less and stop feeding it.For growers outside zones 9-11, a navel on Flying Dragon or another dwarfing rootstock in a large pot is the standard approach to working around the cold limit. When frost threatens, roll or carry the tree into a garage, sunroom, or bright indoor spot, then move it back outside once danger passes. Keep water reduced and hold off on fertilizer while the tree is held cool indoors; this is how navels succeed well north of their in-ground hardiness range.

Move the pot to a protected spot (garage, sunroom, or indoors by a bright window) before the first frost in cold-winter zones, and return it outdoors after frost danger passes. Hold the tree cool and bright, reduce watering, and stop feeding while it is overwintered. This portability is the whole advantage of growing a navel in a container outside its hardiness range.

Hardy to zone 9 in the ground; roots in a pot sit colder than that.

Pot safety

Ask what your balcony or roof can carry

A balcony or roof can only hold so much weight. Before you set heavy pots there, ask a building architect what it can safely carry.Illinois Extension's guidance is to consult a building architect about weight limits before placing heavy pots on a balcony or rooftop garden. It gives no weight figure.

Never grow food in a container with anything toxic in it

Many kinds of containers can be used. Whatever you choose, keep anything toxic out of it, especially if you are growing food.Colorado State accepts nearly any container material but warns against using a container that holds toxic materials, especially for edible plants. Illinois adds that a vegetable container should be free of chemicals toxic to plants or people, and urges caution with treated lumber when growing food. If you cannot account for what a repurposed container once held, that alone is a reason to keep food out of it.

Secure hanging containers well

Fasten hanging baskets and window or rail boxes securely. Think about what is below them too, since they can drip on people or things underneath.Illinois Extension asks growers to secure hanging containers well and to think through the safety issues of hanging them. Placement matters too, since a hanging container can drip onto people or belongings below.

Soil chemistry

Soil pH for orange (navel)

Preferred
6 to 7

Oranges like soil that is slightly acidic, around pH 6 to 7. The main thing to watch for is alkaline (high-pH) soil, common in the desert and inland West, where the tree cannot take up iron and zinc and the leaves turn yellow with green veins. If that happens, use a citrus fertilizer that includes iron and zinc.Navel oranges prefer a slightly acidic soil, roughly pH 6.0 to 7.0, and tolerate a somewhat wider band. The practical issue is high-pH alkaline soil (common in the desert Southwest and interior West), where iron and zinc become chemically unavailable and the tree shows interveinal chlorosis (yellow leaves with green veins) even though the nutrients are present. Correct with chelated micronutrients and a citrus fertilizer that includes them.

Steady hand on the hose

Watering

When & how much
Frequency
Water deeply but not too often. Soak the root zone thoroughly, then let the surface dry out, checking with a finger: when the top inch or two feels dry, it is time to water again. Water more often in hot weather and less in cool weather. Young trees dry out faster than established ones, but still let the surface dry between waterings and never keep the soil constantly wet.Deep and infrequent. Water established trees thoroughly, then let the top inch or two of soil dry before watering again; the interval stretches in cool weather and shortens in heat. Young trees need more frequent water to establish but still on a soak-and-dry pattern, never kept constantly wet.
Amount
Water enough to soak the soil deeply each time, out as far as the edge of the branches, not just a quick splash at the base. A few quick sprinkles do not reach the deep roots, so a long, thorough soak is better.Each irrigation should push moisture down through the full root depth, which for a mature tree means soaking the soil out to the canopy dripline. Frequent shallow sprinklings develop weak surface roots that dry out quickly and leave the tree drought-prone; they also miss the deep roots that anchor the tree and supply it through summer heat.
Method
Use drip emitters or a slow soak from a hose around the outer edge of the branches. Keep water off the trunk and the graft knob, because a wet trunk base can rot. Mulch the area under the tree (but keep the mulch away from the trunk) and keep grass out.Drip or low-volume emitters around the dripline, or a slow soak from a hose, are ideal. Keep water off the trunk and crown, and never wet the graft union, since a constantly damp crown is a direct route to foot rot. Maintain a mulched, grass-free basin, with mulch pulled back from the trunk.
Signs of trouble
Too much water
Signs of too much water are yellow, wilting leaves that do not perk up when you water, dropping leaves, soggy or bad-smelling soil, and gum oozing at the base of the trunk. The key clue is that watering makes the wilting worse, not better.Yellowing leaves that wilt but do not recover after watering, leaf drop, mushy or sour-smelling soil, and gumming at the trunk base are signs of overwatering and incipient foot rot. The diagnostic tell is wilting that worsens, not improves, with more water.
Too little water
Signs of too little water are leaves that curl or look dull and gray, wilting that gets better after you water, fruit dropping early, and dry, hard soil. In hot weather, a thirsty tree drops flowers and fruit and the fruit can sunburn.Leaves that curl, cup, or dull and gray, wilting that recovers after watering, premature fruit drop, and a hard, dry root zone indicate underwatering. In heat, underwatered trees drop flowers and fruit and sunburn exposed fruit.
Feeding rhythm

Feeding

Frequency
split applications through the growing season
Type
citrus (nitrogen-forward, with iron, zinc, and manganese)
When to start
late winter or early spring through summer; stop by late summer

Oranges are hungry for nitrogen and want most of their food during the growing season. Start feeding a grown tree as the weather warms in late winter or early spring, keep it up through summer in a few split doses, and stop by late summer so the new growth has time to toughen up before cool weather arrives. Feed young trees smaller amounts more often to build the framework. If your soil is alkaline, use a citrus fertilizer that includes iron and zinc so the leaves do not yellow. Do not overfeed, since extra soft growth attracts pests.Citrus are nitrogen-hungry and respond to a feeding rhythm concentrated in the growing season. Feed a mature navel from late winter or early spring through summer in split applications, and stop by late summer so new growth hardens before winter cold. Young trees get smaller, more frequent doses to build the framework. Alkaline soils chemically lock up iron, zinc, and manganese, so look for a citrus-formulated fertilizer that supplies all three as chelates and water it in well to reach the roots. Over-fertilizing pushes excess tender flush that draws aphids, leafminer, and psyllid.

N · P · K = 2-1-1

A fertilizer made for citrus (look for one labeled citrus or citrus and avocado); these are higher in nitrogen and include the iron and zinc citrus needsA nitrogen-forward citrus formulation (for example a 2-1-1 ratio) with included micronutrients (iron, zinc, manganese), or a product labeled specifically for citrus and avocado

Who grows well together

Companion planting

Keep grass and lawn out from under an orange tree, since grass steals the water and food the tree's shallow roots need. A ring of mulch (kept back from the trunk) is better than grass right up to the tree. There is no real benefit to planting other things close around citrus. Keep turf and lawn grasses out of the root zone. Grass competes aggressively for water and nutrients in the top soil layer where citrus feeder roots concentrate, and mowing equipment can damage the trunk. A mulched, grass-free area extending to the canopy dripline is the standard recommendation for all citrus. Low-growing nitrogen fixers like white clover or shallow-rooted ground covers planted outside the trunk flare provide living mulch without root competition. Navel oranges are self-fertile and parthenocarpic, so no pollinizer companion is needed. In fact, nearby citrus with fertile pollen may introduce seeds into otherwise seedless fruit.

Other
Comfrey
Comfrey is a leafy plant that grows well near citrus. Its roots reach deep, so it does not fight the tree for water, and a few times a season you can cut the big leaves and lay them on the soil as a mulch that feeds the tree. Plant it out past the trunk, not right against it, and let its flowers bring in helpful bees.Deep roots pull up nutrients, and the leaves can be cut and dropped as a mulch that feeds the tree. Plant it outside the trunk flare, not right against the tree. Traditional
Yarrow
Yarrow is a low, tough plant with flat flower heads that draw in ladybugs, lacewings, and other good bugs that eat aphids and pests off your orange tree. It is shallow-rooted and easygoing, so it does not crowd the citrus roots as long as you keep it out toward the edge of the canopy rather than at the trunk. Let it flower to get the benefit.A low, shallow-rooted plant that draws beneficial insects and does not compete with the citrus roots when kept outside the dripline. Traditional
Fava bean
A cool-season nitrogen fixer that can be grown beyond the dripline as a cover, then cut and dropped to feed the soil without crowding the tree. Research-backed
White clover
A low clover outside the trunk area acts as a living mulch and adds a little nitrogen, without stealing water the way lawn grass does. Research-backed
Nasturtium
An easy flower that covers bare soil and draws in helpful insects. Keep it out from the trunk so it does not crowd the base. Traditional
Marigold
A simple flower that brings in helpful insects and fills bare ground around the tree. Plant it beyond the trunk, not tight against it. Traditional
Keep apart from
St. Augustine grass St. Augustine is a thick, fast-spreading lawn grass, and it is rough on citrus. It soaks up the water and food in the top layer of soil where the tree's roots feed, and it creeps right up to the trunk. Keep a clear or mulched circle around the base of your orange tree and hold the grass back beyond it, since it will keep trying to spread in.A dense, spreading lawn grass that competes aggressively for water and nutrients in the top soil and creeps right up to the trunk. Keep it cleared out to the dripline. Research-backed
Pigeon pea Pigeon pea is a nitrogen-fixing legume, so it looks like a natural cover crop for citrus, but it carries a specific strike against it. Research testing whether legumes shelter the citrus root weevil (Diaprepes abbreviatus) found that pigeon pea actually supported the weevil's larval development, sustaining a pest whose larvae feed on citrus roots instead of starving it out. The important context for most navel growers: this weevil is established in Florida and the Caribbean, not in the arid citrus regions of California and Arizona, so if you are growing navels in the West, pigeon pea's worst property is not a live threat in your area. The reason to skip it anyway is that the same research also flagged possible chemical interference from pigeon pea on citrus roots, which is not regional, and you give up nothing by choosing a cool-season legume like fava or a clover cover instead. Those deliver the same nitrogen benefit with no root-pest baggage. Research-backed
Turf grass Lawn grass under the tree steals the water and food the orange's shallow roots need. A ring of mulch, kept back from the trunk, is better than grass. Research-backed
Bermuda grass A tough, spreading lawn grass that competes hard for water and is difficult to keep out of the root zone. Clear it out to the edge of the branches. Research-backed
Provenance tagged inline · see methodology for the labeling system Key
Harvest signals

When to pick

Pick oranges by taste, not just by color. The skin turns orange as the nights get cold, but in mild or humid areas it can still look a little green even when the fruit is ripe, and an orange-looking fruit in a cool-summer area might still be sour. So taste one to decide. The best part about navels is that the fruit keeps on the tree for weeks or months and gets sweeter, so you can pick a few at a time and there is no rush. The exception is the hot, dry desert, where fruit left on too long dries out inside, so pick it during its best window there.Harvest navels by taste, not color alone. Rind color develops as nights cool, but in mild and humid climates the rind can stay green-tinged on fully ripe fruit (the Florida and Hawaii nuance), and a fully colored rind does not guarantee sweetness in a cool-summer climate. Taste-test a fruit to judge readiness. The great advantage of navels is the long on-tree hold: fruit holds and continues to sweeten on the tree for weeks to months, so the harvest window is forgiving and you can pick over an extended period. The exception is hot, dry desert climates, where fruit left too long granulates and dries, so pick within the prime window there.

Yield

What to expect

How much fruit a full-grown orange tree produces depends on the variety, climate, and tree size. A small dwarf tree in a pot makes much less, but still enough to enjoy.A mature navel's yield varies widely by variety, climate, tree size, and rootstock. Dwarf container trees yield far less but still produce a meaningful home crop.

An orange tree hits its full crop around five to eight years old and then produces well for decades. It is normal for the crop to be a little heavier some years and lighter others, so do not worry about that.Trees reach full production around the fifth to eighth year and then bear heavily for decades. Navels show mild natural alternate bearing, with somewhat lighter and heavier crops in alternating years, which is normal and not a problem to correct. Young trees need their first-year energy in roots and branches, not fruit. Snap off any flowers that appear in the first season to redirect that energy into the framework. Fruit will start coming around year two or three, with a real crop building as the tree grows bigger. Building up first is what gets you more oranges in the long run.Strip any flowers that set in the first season so the tree puts its energy into roots and canopy framework rather than fruit. No crop is expected anyway in year one, and allowing early fruiting only slows establishment. Light bearing typically begins in year two or three, with a full crop building as the tree matures. The investment in the first season pays back in stronger, earlier-peaking production.

Off the vine

Storing your harvest

Room temp
Once picked, oranges last about one to two weeks on the counter. But the best way to store them is to leave them on the tree, where they keep and get sweeter for weeks or even months.Picked navels keep about one to two weeks at room temperature. Their bigger storage advantage, though, is on the tree: navels hold and continue sweetening on the tree for weeks to months, so the tree itself is the best short-term storage.
Fridge
In the fridge, oranges last three to four weeks, up to about six weeks in the crisper drawer. Keep them loose or in a bag with holes so they do not get damp and moldy.Refrigerated, navels keep three to four weeks, and up to about six weeks in a crisper drawer. Store them loose or in a perforated bag so they do not sweat; do not seal them airtight.
Freezer
Whole oranges do not freeze well. You can also freeze the zest (the colored part of the peel) for cooking.Whole navels do not freeze well. Segments can be frozen in syrup. Zest can be frozen for baking.
When something goes wrong

Common problems

The oranges are sour and pale even though the tree seems fineFruit stays sour and pale even though the tree looks healthy
01 of 05
What happened This is the main thing that can go wrong with a navel, and it is about your climate, not anything you did. To get sweet, orange fruit, a navel needs a lot of summer heat. In cool coastal or foggy areas the tree looks healthy and makes fruit, but there is not enough heat to make the fruit sweet, so it stays sour and pale no matter how well you care for it.This is the navel's defining failure mode and it is a climate limitation, not a care mistake. Developing the full sugar and deep color of a navel requires substantial accumulated summer heat. In cool coastal and fog-influenced climates the tree grows, blooms, and sets fruit normally, but heat is insufficient for sugar to develop, so the fruit remains acidic and stays pale or green-tinged regardless of feeding, watering, or patience. Next season There is no way to fix a lack of heat with watering or feeding. If you live in a cool coastal area, expect navels to be tart, and a hot south-facing wall might help a little. If you are in a warm area and the fruit is just not ripe yet, give it more time on the tree, since navels keep getting sweeter.There is no cultural fix for insufficient heat. If you are in a cool-coast climate, expect tart fruit from standard navels and consider whether a warmer microclimate (a south-facing, heat-trapping wall) helps at the margin, or grow citrus types better suited to cool summers. In a heat-adequate climate, simply allow the full long-hang ripening window, since navels sweeten further the longer they hold.
A lot of flowers or little fruit fell offHeavy flower or young-fruit drop, often after a spring heat spike
02 of 05
What happened Losing a few flowers and tiny fruit is normal, but losing a lot usually means the watering bounced between too dry and too wet, a hot spell (into the 90s) struck during bloom, or the tree was underfed. This is common in hot-spring desert and inland areas.A measure of flower and post-set drop is the tree thinning itself and is expected, but a heavy loss usually points to the root zone swinging between dry and waterlogged, a sudden spring heat spike into the 90s°F during or right after bloom, or nutrient stress carried through flowering. In hot-spring desert and interior climates this drop is a recurring challenge, and a navel holds its crop best on even moisture and steady feeding. Next season Next time, keep the watering steady so the soil is neither bone dry nor soggy, and water extra during a hot spell while the tree is in bloom. Keep feeding through flowering. You cannot control the weather, but even soil moisture is the best thing you can do.Keep the watering even so the root zone neither bakes dry nor sits saturated, and bump it up during a heat spike to cushion the tree. Maintain steady citrus feeding from bloom through fruit set. The weather is out of your hands, but consistent soil moisture is the single strongest lever against heat-spike drop.
The fruit looks ripe but is dry and pithy insideFruit is dry, pithy, or granulated inside despite looking ripe outside
03 of 05
What happened Sometimes fruit that looks ripe on the outside is dry and pithy inside. This usually happens to fruit left on the tree too long in a hot, dry climate, especially in the desert late in the season. Heat, dryness, and over-ripeness are the causes, and the skin can look fine even when the inside has dried out.Granulation (juice vesicles drying and hardening) and general drying-out tend to appear in fruit left on the tree well past peak in hot, dry climates, and in low-desert conditions fruit can dry on the tree late in the season. Over-mature fruit, water stress during late development, and intense heat and low humidity all contribute. The rind can look perfectly normal while the interior loses quality. Next season In hot, dry areas, pick the fruit during its best window instead of leaving it on the tree for months, and keep watering steadily late in the season. Taste a fruit now and then so you can pick them at their best before they dry out.In hot, dry climates harvest within the prime window rather than relying on the full extended hold that works in milder areas, and keep late-season irrigation steady to limit water stress. Taste-test through the season so you catch fruit at peak before granulation sets in.
The tree is dropping a lot of leavesSudden leaf drop and a thinning canopy
04 of 05
What happened Two things often cause leaf drop. One is cold: after a frost, an orange (which never goes dormant) can wilt and drop leaves a few days later. The other is too much water or poor drainage, which rots the roots and turns leaves yellow, and the clue there is that watering does not help, it makes it worse. A long heat wave can also cause some leaf drop.Two common causes look different but both end in leaf drop. Cold injury follows a frost event, with leaves wilting, browning, and dropping days afterward on an evergreen tree that never goes dormant. Overwatering and poor drainage are the other frequent culprit: saturated roots and incipient Phytophthora foot rot cause yellowing and drop, and the tell is leaves that wilt but do not recover after watering. Sustained heat stress can also force some defensive leaf drop. Next season Figure out the cause first. If it was frost, protect the tree better next time and wait until spring to trim damaged branches so you can see what lived. If it is overwatering, water less, make sure the soil drains fast, and check that the graft knob is not buried. If it is heat, water steadily during hot weather.Distinguish the cause before acting. For cold, improve frost protection and avoid pruning damaged wood until spring growth shows what survived. For overwatering, back off irrigation, confirm sharp drainage, and check that the graft union and crown are not buried, which is the foot-rot risk. Treat heat-driven drop with steady irrigation through hot spells.
Leaves turning yellow but the veins stay greenYellowing leaves with green veins (iron or zinc chlorosis)
05 of 05
What happened When leaves turn yellow but the veins stay green, especially on new growth, the tree is short on a micronutrient, usually iron or zinc. This happens a lot on alkaline (high-pH) soils, common in the desert and the inland West, where the nutrient is in the soil but the tree cannot take it up. It looks different from an even all-over yellowing (which is usually nitrogen) and from the blotchy yellowing of citrus greening.Yellow leaves with a network of green veins, especially on new growth, signal a micronutrient deficiency, most often iron or zinc, that is common on alkaline, high-pH soils where these nutrients are present but chemically unavailable to the tree. This is widespread in desert and interior-West soils. It is distinct from the symmetric overall yellowing of nitrogen deficiency and from the asymmetric blotching of greening disease. Next season Fix it with a chelated iron or zinc product, sprayed on the leaves for a fast response and added to the soil for the long run, and use a citrus fertilizer that lists micronutrients.Correct with a chelated iron or zinc product, applied as a foliar spray for a quick response and to the soil for longer-term supply, and use a citrus fertilizer that includes micronutrients.
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The usual suspects

Pests & diseases

Pests
Asian citrus psyllid
P · 01
Symptoms This tiny brown insect has a distinctive resting posture: it perches on new leaves at an angle, with its rear end raised and pointed upward, which is your identification clue. The young ones produce little waxy white threads and cause the new leaf tips to curl. The real danger is not the feeding itself but a fatal disease the psyllid spreads, citrus greening, so it is worth acting on even where the pest is uncommon.The psyllid itself is a tiny mottled-brown insect, about an eighth of an inch, that feeds tilted up at a 45-degree angle on new flush, a posture no other citrus pest shares. Its nymphs produce distinctive waxy tubules and curl tender new growth; heavy feeding twists and notches expanding leaves. The insect matters less for its direct damage than for what it carries: it is the vector of Huanglongbing (citrus greening), the most serious citrus disease worldwide. Scout the youngest flush, where it concentrates. Cause The psyllid breeds on fresh new leaves, so it builds up fastest when the tree is putting out tender growth in warm weather. It has spread across the southern states, and any psyllid you find could be carrying the disease.Adults lay eggs only on new flush, so populations track flushing cycles and explode in warm weather when trees push tender growth. The pest has spread through most citrus-growing regions of the southern United States; in much of California and the Gulf states it is now established, and any psyllid should be assumed a potential disease carrier. Organic treatment Spray horticultural oil or insecticidal soap on the new growth to knock back the young psyllids, and repeat each time fresh leaves appear. Hold off on oil when it is hot, above roughly 95°F, or when the tree is short on water, since either condition lets oil burn the leaves. Also report any psyllids or signs of the disease to your local farm advisor or county office, because it is closely tracked.On a backyard tree, horticultural oil and insecticidal soap applied to new flush reduce nymphs; thorough coverage of tender growth is key, and repeat as each flush emerges. Do not apply oil above 95°F or to a drought-stressed tree. Most importantly, report suspected psyllids or greening symptoms to your county agricultural office, since this is a regulated pest. Prevention Buy certified citrus from a trusted nursery, and never carry citrus plants or cuttings out of a quarantine zone, because that is how the pest and its disease spread. Check the new leaves often in warm weather. If citrus greening is in your area, follow local guidance on controlling the psyllid.Buy only certified citrus from a reputable nursery and never move citrus plants or leaves out of a quarantine area, which is the main way the pest and disease jump regions. Inspect each new flush in the warm season. Conserve the natural enemies (a parasitic wasp, Tamarixia, and general predators) that suppress it. Where the disease is present, area-wide psyllid control is the front line.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Beneficial predators

    Leave the helpers in the tree alone to work. A small parasitic wasp called Tamarixia attacks psyllid nymphs, meaning the young stages, and general predators feed on them too, so keeping broad, strong insecticides out of the canopy protects the control you already have.Conservation of the resident enemy complex, Tamarixia plus the general predators, is the standing suppression on a backyard tree. Broad-spectrum material removes it, and the psyllid rebuilds on each new flush faster than its enemies do.

  2. Insecticidal soap

    On a backyard tree, insecticidal soap sprayed onto the new growth knocks back the young psyllids. It works only where it lands, so wet the tender shoot tips and leaves thoroughly, and spray again each time a fresh round of leaves pushes out.Soap applied to expanding flush reduces nymphs, and coverage of the tender growth decides the result, since the material is contact-only. Repeat with each flush rather than treating once, because the population tracks flushing cycles.

  3. Horticultural oil

    Horticultural oil, a light spray oil that coats insects rather than poisoning them, does the same job on the new flush. Hold off in hot weather and on a tree that is short of water, since oil can burn foliage under either condition, and go back over the tree as fresh leaves appear.Oil on new flush is interchangeable with soap against nymphs, with the same coverage requirement and the same repeat schedule through successive flushes. Withhold it in hot weather or on a drought-stressed tree, where it turns phytotoxic.

No spray for this one. Prevention is the control.

Citrus leafminer
P · 02
Symptoms You will see squiggly silver trails snaking through the new leaves, often with the leaf edge curled up. A tiny caterpillar makes these tunnels inside young leaves only. It looks alarming but rarely hurts an established tree, though it can set back a small young one.Silvery, serpentine tunnels winding through new leaves, with a thin dark line of frass down the center of each mine, and leaf margins that curl and pucker around the damage. The larva mines only young, expanding foliage; hardened mature leaves are not attacked. On established trees the injury is cosmetic, but on young trees pushing lots of flush it can slow growth and the curled tissue can shelter other pests. Cause A tiny moth lays its eggs on the newest leaves, and the larvae tunnel inside them. They breed fast in warm weather, so the worst damage shows up on the late-summer growth.A small moth lays eggs on tender new flush, and the larvae mine between the leaf surfaces. Generations cycle quickly in warm weather, so damage peaks on the late-summer and fall flushes rather than the spring growth. Organic treatment Usually no treatment is needed, and spraying can kill the good bugs that control it. On a small young tree you want to protect, light horticultural oil on the new leaves discourages the moth. Only spray oil in mild conditions, not in high heat or on a thirsty tree, and leave the tunneled leaves on the tree.Chemical control is rarely warranted, and broad-spectrum sprays undermine the parasitic wasps that naturally suppress leafminer populations. For young trees, where the canopy is small enough that leafminer damage slows establishment, a lightweight horticultural oil applied at bud break can discourage adults from laying eggs on the new flush; repeat as each flush emerges because oil breaks down quickly. Follow label heat restrictions and do not spray above 95°F. Leave mined leaves in place, as they continue photosynthesizing. Prevention Do not over-fertilize or prune a lot in summer, because that creates the tender new leaves the moth needs. On a healthy grown tree, it is best to just live with the trails, since helpful wasps keep it in check.Avoid pushing excess tender flush with heavy nitrogen or unnecessary summer pruning, since the moth needs young leaves to breed. Tolerate cosmetic mining on bearing trees; resident parasitic wasps usually provide good control if broad-spectrum sprays are avoided.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Balance nitrogen

    Go easy on fertilizer and skip unnecessary summer pruning. The moth can only lay on soft new leaves, the flush, so anything that forces extra rounds of tender growth hands it more places to breed. Leave the tunneled leaves on the tree as well, since they keep feeding it.Restrained nitrogen and no unnecessary summer pruning keep flush synchronized and shorten the window of mineable tissue; hardened mature leaves are not attacked. Mined leaves continue photosynthesizing, so stripping them costs the tree more than the mines do.

  2. Beneficial predators

    On a grown tree the silvery trails are worth living with. Small parasitic wasps attack the larvae inside the leaves and usually keep this in check, and a broad, strong insecticide takes those wasps out along with the pest.Resident parasitoids give good control where broad-spectrum sprays are avoided, which is why chemical treatment is rarely warranted on a bearing tree. The injury there is cosmetic, so conservation costs nothing and holds.

  3. Horticultural oil

    A young tree is the exception, since heavy mining can slow one down while it is still building its framework. A lightweight horticultural oil, a light spray oil, put on the new leaves at bud break discourages the moth from laying. Oil breaks down quickly, so recoat as each fresh flush emerges, and follow the label heat limits rather than spraying in high heat or on a thirsty tree.Reserve oil for young trees, where mining slows establishment. Applied to emerging flush at bud break it discourages egg-laying, and the short residual means it follows each flush rather than being applied once. Observe the label heat restrictions and withhold it on a drought-stressed tree.

No spray for this one. Prevention is the control.

Scale insects
P · 03
Symptoms Scale look like little hard or waxy lumps that sit still on twigs and the undersides of leaves, so it is easy to think they are just part of the branch. The softer kinds make the leaves tacky and a sooty black coating grows on that stickiness. Ants are often crawling around them.Scale appear as fixed, non-moving bumps clustered on twigs, along the leaf midrib, and beneath the leaves. The armored types form firm gray or brown shells that look almost like raised bark, while the softer types are plumper and somewhat glossy. The soft kinds give themselves away by the honeydew they secrete, which leaves foliage tacky and grows a black sooty film, and you will often find ants patrolling the colony for that sugar. Where numbers run high, expect mottled yellow leaves, premature leaf fall, and dieback at the twig tips. Cause Scale are little insects that feed on the tree's sap. They get worst when ants are around, since the ants protect them from the helpful bugs that eat scale.A mix of armored and soft scale species tap into the tree and feed on its sap. They get the upper hand on trees that are dusty, crowded, or patrolled by ants, because the ants drive away the ladybugs and parasitic wasps that would otherwise thin the colony. Organic treatment Coat the lumps with horticultural oil, making sure to reach the backs of leaves and the twigs. Save the spray for cooler, well-watered days, never above roughly 95°F or on a drought-stressed tree, or it can scorch the foliage. Spray again later as new ones appear.A thorough horticultural oil application, narrow-range petroleum or neem, smothers the scale and is the usual home remedy; the key is wetting every surface, especially twig undersides and leaf backs. Skip oil above roughly 95°F or on a tree that is drought-stressed, since heat plus oil scorches foliage. Plan a follow-up as fresh crawlers hatch. Prevention Keep ants from climbing the tree by wrapping a sticky band around the trunk, which lets the good bugs control the scale, and look over any new tree for lumps before planting it.Keep the tree vigorous and rinse dust off the canopy, and cut off the ants with a sticky trunk band so the resident beneficial insects can do the work. Look any incoming nursery tree over carefully, because scale frequently hitchhikes in on new stock.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Ant exclusion

    Look for ants patrolling the trunk. While they are working the tree they drive off the ladybugs and parasitic wasps that would thin the colony, so shutting them out is what changes the situation. Collar the trunk with heavy paper, duct tape, or fabric tree wrap and put the sticky material on that collar, since sticky goo straight on bark can injure a trunk. Then trim back any low branch touching the ground, a wall, or a neighboring plant, because ants walk around a band by those routes.Ant tending is what holds armored and soft scale above the level resident predators and parasitoids would allow, so breaking canopy access restores that control at no cost. UC IPM directs that the sticky material go on a collar of heavy paper, duct tape, or fabric tree wrap rather than on bare bark, which it can injure. Close the bypass routes in the same pass, since a branch bridging to soil, a wall, or an adjacent plant makes the band moot.

  2. Beneficial predators

    With the ants out of the way, the ladybugs and tiny wasps already living in the tree do much of the work for free. Keep broad, strong insecticides off the tree so they stay.Predators and parasitoids thin colonies on an unstressed tree, so the operative choice is keeping broad-spectrum material out of the canopy rather than adding anything to it. Dusty, crowded trees are where scale gets the upper hand.

  3. Horticultural oil

    If the bumps keep spreading, coat them with horticultural oil, a light spray oil that smothers insects instead of poisoning them. It works only where it lands, so wet the twigs and the backs of the leaves. Save it for cooler days on a well-watered tree, since heat plus oil can scorch foliage, and go over the tree again as new young scale hatch out.A narrow-range petroleum or neem oil smothers settled scale, so coverage of twig undersides and leaf backs governs the outcome more than rate does. Withhold it in hot weather or on a drought-stressed tree, where foliage injury follows, and plan a follow-up as fresh crawlers hatch.

No spray for this one. Prevention is the control.

Aphids
P · 04
Symptoms Look for clusters of tiny soft-bodied insects, often green or black, packed onto the newest leaves and flower buds, causing the tips to curl. They secrete a sticky coating that ants follow and that leads to a black sooty film. Navel oranges are most vulnerable during the spring and fall flushes when tender new growth is available.Clusters of soft-bodied green, black, or brown aphids on the youngest flush and flower buds, with curled, distorted new leaves and a sticky honeydew coating that draws ants and grows sooty mold. Spring and fall flushes are the targets. One species, the brown citrus aphid, is also a vector of citrus tristeza virus, which raises the stakes where that disease is a concern. Cause Aphids multiply very fast on soft new growth in mild weather, and ants protect them. Too much fertilizer makes extra tender leaves that draw them in.Aphids reproduce explosively on tender new growth in mild weather and are tended by ants for their honeydew. Lush, over-fertilized flush is especially attractive, and ant protection lets colonies outrun their natural enemies. Organic treatment Spray them off with water, or use insecticidal soap or horticultural oil, getting under the curled leaves. Keep oil for mild days only, not in high heat or on a stressed, dry tree, and avoid harsh sprays that kill the good bugs.A forceful water spray, insecticidal soap, or horticultural oil controls aphids; cover the undersides of curled leaves. Repeat as needed. Observe oil heat limits (not above 95°F or on stressed trees). Preserve natural enemies by skipping broad-spectrum insecticides. Prevention Do not over-fertilize, which makes the soft growth aphids love, and keep ants out so ladybugs and other helpers can eat them. A blast of water from the hose usually clears them off.Avoid forcing excessive tender flush with heavy nitrogen. Control ants so ladybugs, lacewings, and parasitic wasps can suppress colonies. A strong jet of water knocks aphids off new growth and is often all that is needed.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Balance nitrogen

    Ease off high-nitrogen feeding. Heavy fertilizer keeps pushing out soft new leaves, and lush growth like that is what aphid colonies pile onto.Excess nitrogen extends the run of tender flush colonies build on, so restraint narrows the susceptible tissue rather than acting on the insects. Pressure on navels concentrates in the spring and fall flushes, which is when the feeding habit pays.

  2. Water spray

    Knock the clusters off the shoot tips with a strong jet from the hose. On an established tree that is often the whole job, and unlike a spray it leaves the helpful insects on the same growth alone. Do it early in the day so the leaves dry.A forceful water jet dislodges colonies from tender shoots without setting back the natural enemies working the same flush. Aim it at the growing points and the undersides of curled leaves and repeat, rather than escalating while numbers are still low, and time it so foliage dries.

  3. Ant exclusion

    Check the trunk for an ant trail. Ants harvest the sticky honeydew the aphids give off and defend them from the ladybugs, lacewings, and parasitic wasps that would otherwise clear them. Band the trunk with a collar of heavy paper, duct tape, or fabric tree wrap and put the sticky material on the collar rather than on bare bark, then cut back low branches that bridge to the ground, a wall, or another plant. Where no ants are working the tree, this one does not apply.Ant protection is what lets colonies outrun their natural enemies, so exclusion shortens an outbreak rather than treating it. Apply the sticky material to a paper, tape, or fabric collar instead of bark, and close the branch bridges to soil, wall, or neighboring plants that route ants past the trunk. Where no trail is present this is not the situation it addresses.

  4. Beneficial predators

    Ladybugs, lacewings, and small parasitic wasps usually bring an aphid outbreak down on their own, so low numbers are worth tolerating. Broad-spectrum sprays set those helpers back and are worth leaving out.Resident lady beetles, lacewings, and parasitoids suppress colonies once ant tending is broken, which is the argument for tolerating low numbers on a bearing tree. Skipping broad-spectrum insecticides is what preserves them.

  5. Insecticidal soap

    For a heavy infestation, insecticidal soap sprayed straight onto the clusters brings numbers down. Get under the curled leaves, since it kills only what it wets, and repeat as needed.Soap is contact-only, so working it into the curled tissue where colonies shelter matters more than volume, and repeats follow the flush rather than the calendar.

  6. Horticultural oil

    Horticultural oil, a light spray oil, is the other option for a heavy outbreak. It coats the aphids rather than poisoning them, so cover the shoot tips and the undersides of curled leaves. Keep it for mild days and a well-watered tree, since oil in high heat or on a thirsty tree can scorch the foliage.Oil is interchangeable with soap on a heavy infestation, with the same coverage requirement into curled tissue. Withhold it in hot weather and on a drought-stressed tree, where it injures foliage, and keep broad-spectrum insecticides out of the canopy so the natural enemies survive the intervention.

No spray for this one. Prevention is the control.

Citrus red mite
P · 05
Symptoms Look for leaves that turn a dull, speckled, silvery color, sometimes with tiny red dots moving on them (a hand lens helps). Mites get worse when it is hot, dry, and dusty. A lot of them can bronze the leaves and cause some to drop.A fine stippling or silvering on leaves and sometimes fruit rind, with tiny dark-red mites and their cast skins visible on leaf surfaces under a hand lens. Heavy populations bronze the foliage and can cause leaf drop. Mites flare in hot, dusty, dry conditions and after broad-spectrum sprays kill their predators, so outbreaks are often a sign the tree is dust-stressed or was over-sprayed. Cause These mites love hot, dusty conditions and build up fast on stressed trees. Dusty trees and trees that have been sprayed with strong insecticides (which kill the helpful mites) get the worst of it.Citrus red mite thrives in heat and dust and reproduces rapidly on stressed trees. Dusty roadside or driveway trees and trees sprayed with broad-spectrum insecticides (which remove predatory mites) are the most prone to damaging populations. Organic treatment Usually the damage is just cosmetic and needs nothing. If there are a lot of mites, horticultural oil works, but timing is tricky: mites peak in hot weather, which is the riskiest time to oil a tree. Only spray when it has cooled off, never on a hot, dry, stressed tree.Damage is usually cosmetic and rarely needs treatment. If populations are heavy on a stressed tree, horticultural oil provides control; observe heat limits strictly, as mite outbreaks coincide with the hot weather when oil is riskiest. Do not apply oil above 95°F or to a drought-stressed tree. Prevention Rinse dust off the leaves during hot dry weather and keep the tree watered, because a healthy tree handles mites better. Avoid strong insecticides that kill the good mites.Hose dust off the canopy in hot, dry spells and keep the tree well watered, since vigorous trees tolerate mites better. Avoid broad-spectrum insecticides that destroy the predatory mites providing natural control.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Even watering

    Keep the tree watered steadily rather than letting it swing between soaked and bone dry. These mites build up fastest on a hot, dry, stressed tree, and a vigorous one puts up with them better.Water stress is a principal driver of buildup, so steady soil moisture is the baseline control rather than an afterthought. Populations climb through hot, dry spells, which is also when a stressed tree has the least tolerance for the feeding.

  2. Water spray

    Hose the dust off the canopy during hot, dry weather. Dust is one of the conditions these mites thrive in, and rinsing the leaves takes it away without harming the good mites that eat them.Rinsing the canopy strips the dust layer that favors buildup, which is why dusty roadside and driveway trees carry the heaviest populations. It suppresses numbers without the predator loss that follows a spray.

  3. Beneficial predators

    Predatory mites eat the pest mites for free, and strong broad-spectrum insecticides kill them. Leaving those sprays out is what keeps a light speckling from turning into a heavy infestation.Predatory mites are the standing check, and broad-spectrum insecticides remove them, which is the usual route into a damaging population. An outbreak is often the sign that a tree was over-sprayed or is dust-stressed rather than that it needs treating.

  4. Horticultural oil

    Most of the time the speckling is only cosmetic and needs nothing. If a stressed tree is carrying a lot of mites, horticultural oil, a light spray oil, works on contact, so cover the leaf surfaces. The timing is awkward: mites peak in hot weather, which is when oil is riskiest, so wait for it to cool off and water the tree well first.Treatment is seldom justified, the injury being largely cosmetic. Where populations are heavy on a stressed tree, oil gives control by contact and coverage, but the heat limits bind hardest here, since outbreaks coincide with the weather that makes oil phytotoxic. Withhold it in hot weather and on a drought-stressed tree.

No spray for this one. Prevention is the control.

Katydids and fruit-surface chewers
P · 06
Symptoms You may find ragged bites out of young leaves, or smooth shallow scars on the skin of the fruit where something chewed it when it was small. On a navel this is only skin-deep: the fruit inside is fine, it just looks marked.Irregular chewed notches on young leaves and, more conspicuously, smooth shallow gouges or healed scars on the rind of developing fruit, where a katydid or similar chewing insect fed when the fruit was tiny. The damage scars over and grows out as the fruit expands, so it is a cosmetic, surface-only blemish that does not reach the flesh of a navel. Cause Katydids and a few other leaf-chewing insects nibble soft leaves and tiny fruit in spring and early summer. There are usually only a few of them, even though the scars look like a lot.Katydids and other occasional chewing insects feed on tender foliage and very young fruit in spring and early summer. Populations are usually low and sporadic in a backyard, and the visible scarring is out of proportion to the actual number of insects. Organic treatment Spraying is almost never worth it for marks on the skin. Just pick off the bugs by hand. Only consider a spray if a small tree is being stripped of leaves, and then pick a targeted one rather than a harsh insecticide.Treatment is rarely justified for cosmetic rind scarring. Hand-picking handles the occasional katydid. Reserve any spray for genuine defoliation of a young tree, and prefer a targeted product over a broad-spectrum insecticide that would disrupt the citrus natural-enemy complex. Prevention Caterpillar chewing rarely warrants intervention. An established tree outgrows the leaf notches quickly, and natural predators, including birds and beneficial wasps, keep populations in check on their own. If you spot a caterpillar on a small young tree, you can simply pick it off by hand.No action is generally needed on a home tree. Healthy trees outgrow the cosmetic injury, and the chewers are kept in check by birds and general predators. Hand-pick if a particular insect is abundant on a small tree.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Handpick

    If a chewer is abundant on a small young tree, pick them off by hand. That is enough for the occasional katydid, and on an established tree the marks on the skin are not worth chasing.Hand-picking covers the occasional katydid on a small tree and is the proportionate response, since populations are usually low and sporadic and the visible scarring is out of proportion to the number of insects. On a bearing tree the rind injury scars over and grows out as the fruit expands.

  2. Beneficial predators

    Most of the time the answer is to leave it be. Birds and other general predators keep these chewers in check on their own, and a healthy tree grows past the leaf notches.Birds and the general predator complex hold these sporadic chewers down without intervention, and a vigorous tree outgrows the cosmetic injury. A broad-spectrum insecticide would disrupt the citrus natural-enemy complex for damage that stays on the surface of the rind, which is the argument for restraint.

No spray for this one. Prevention is the control.

Diseases
Huanglongbing (citrus greening, HLB)
D · 01
Symptoms The classic sign is a leaf that is yellow in a blotchy, uneven pattern, with the yellow on one side of the leaf not matching the other (a nutrient problem is usually even on both sides). Fruit stay small, lopsided, green on the bottom, and taste bad. There is no cure, and the tree slowly dies. It is the worst citrus disease there is.Blotchy, asymmetric yellowing of leaves that does not mirror across the midrib (distinguishing it from a nutrient deficiency, which is usually symmetric), yellow shoots, and corky, enlarged leaf veins. Fruit are small, lopsided, fail to color fully, stay green at the bottom, and taste bitter and salty; seeds often abort. The tree declines over several years and there is no cure. This is the most destructive citrus disease worldwide. Cause Bacteria spread by the Asian citrus psyllid as it feeds on new shoots clog the tree's vascular system, blocking the flow of nutrients to roots and fruit. No treatment can reverse the infection; an affected tree is a permanent source of disease spread. The entire management strategy is preventing psyllid feeding and removing any confirmed tree before it extends the outbreak.Candidatus Liberibacter asiaticus, the bacterium behind citrus greening, spreads tree to tree via the Asian citrus psyllid feeding on new growth. Inside the tree it clogs the phloem so nutrients cannot reach roots and fruit. No treatment can clear the infection once established, so management is entirely about suppressing the psyllid and removing confirmed trees before they seed the pest further. Organic treatment There is no treatment that saves an infected tree. Focus entirely on prevention: keep the psyllid off your trees with regular inspection and treatment, and if a tree is diagnosed with citrus greening, remove it promptly to protect your neighbors' trees and the surrounding area. An infected tree left in place becomes an ongoing source of psyllid pressure.There is no cure and no organic remedy for an infected tree. Management is prevention and vector control only: protect trees from the psyllid, and remove and properly dispose of confirmed-infected trees promptly so they cannot serve as a reservoir for further spread. Prevention Buy only certified clean trees, never move citrus out of a quarantine zone, and control the psyllid that spreads it. Check your tree often, and report anything that looks like greening to your local agricultural office, because removing infected trees quickly is what protects everyone's citrus.Plant only certified disease-free nursery trees, never move citrus out of quarantine areas, and control the psyllid vector aggressively where it is present. Inspect trees regularly and report suspected greening to your county agricultural commissioner, since coordinated removal of infected trees is the only effective area-wide defense.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Certified clean stock

    Buy a tree certified free of this disease, and do not bring citrus plants or cuttings in from a quarantine zone. The bacteria travel in the plant itself as well as in the psyllid that carries them, so starting with clean stock is the prevention step most fully in your hands.Certified disease-free nursery stock is the controllable half of the exposure, since the pathogen moves in propagation material as readily as it does in the vector. Observing the restriction on moving citrus out of quarantine areas is the other half, and both are settled before anything is in the ground.

  2. Garden sanitation

    There is no cure for a tree that has greening, and an infected tree declines over several years. If yours is confirmed infected, take it out promptly and dispose of it properly, because a tree left standing keeps supplying the psyllid with bacteria to carry to trees nearby. Check your tree regularly, and report anything that looks like greening to your county agricultural commissioner, since coordinated removal is what protects an area.Removal of a confirmed infected tree is inoculum management rather than treatment: nothing clears the infection once it is established, and a declining tree stays an acquisition source for the vector while it stands. Inspect regularly, report suspect symptoms to the county agricultural commissioner, and follow the regional program's direction on confirmation and disposal.

No spray for this one. Prevention is the control.

Phytophthora foot rot, root rot, and gummosis
D · 02
Symptoms This soil water-mold disease shows up as gum oozing low on the trunk, dark mushy bark right at ground level, and a tree that gradually yellows and gets sparse. The big clue: the leaves yellow and wilt but do not bounce back when you water, which means rot rather than thirst.Watch for gum weeping from the lower trunk and crown (gummosis), and bark at the soil line that turns dark and water-soaked, then later splits and dries as a sunken lesion (foot rot). When the disease works on the feeder roots instead, the tree fades slowly, with leaves yellowing and the canopy thinning out (root rot). The diagnostic clue is foliage that yellows and wilts yet fails to perk up after irrigation, which sets it apart from simple drought, and lesions can climb from the crown onto the lower scaffold limbs. Cause It lives in the soil and travels in standing water. It gets going when the ground stays wet, when soil or mulch is mounded up around the trunk, or when the graft union ends up buried. The graft union is that knob low on the trunk, the point where the fruiting variety was joined onto the roots, and it needs to stay above the soil. Watering young trees too much is the usual trigger.Phytophthora organisms, which are water molds rather than true fungi, live in the soil and release swimming spores whenever conditions turn wet; those spores splash up onto the trunk or move through saturated ground to the roots. The disease is set up by soggy or poorly draining soil, soil or mulch heaped against the trunk, a graft union buried below grade, and the chronic overwatering that young trees so often receive. Organic treatment Sort out the drainage or stop the overwatering first, or nothing else will work. For a gummy patch on the trunk, you can gently trim away the dark dead bark down to healthy bark and let it dry out. A serious root case is tough to cure, so getting the planting right up front is what counts.Fix the water and drainage problem before anything else, since the tree cannot recover while the roots stay wet. On a fresh trunk lesion you can pare back the dark, dead bark to a rim of healthy green tissue and let the area dry; opening a buried crown to the air sometimes arrests it. Once root rot is advanced on an established tree it is hard to turn around, which is exactly why the planting practices matter so much. Prevention Prevention is mostly in the planting. Put the tree up on a small mound, hold the graft union clear of the soil (UF/IFAS says more than six inches above it), make sure water drains off fast, hold mulch a hand's width away from the trunk, and never point water at the base. This is the disease most worth preventing from the start.Engineer this one out when you plant, because that is the only reliable defense. The goal is a crown that drains immediately: build a low mound or berm, position the tree so only the uppermost roots are covered, and keep the graft union at least six inches above finished grade per UF/IFAS guidance. Grade the surrounding soil for positive drainage away from the base, hold mulch a foot back from the trunk, and keep drip emitters out of the crown zone. A Phytophthora-tolerant rootstock such as Carrizo, Swingle, or trifoliate provides an additional layer of protection.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Improve drainage

    Design this one out at planting, because that is the defense you can count on. Set the tree on a low mound so the crown drains right away, with only the topmost roots covered, and grade the surrounding soil so water runs away from the base. Keep the graft union, the knob low on the trunk where the fruiting variety was joined to the roots, clear of the soil; UF/IFAS puts that at six inches or more above finished grade. Hold mulch a hand's width back from the trunk and keep drip emitters out of the crown zone. Overwatering a young tree is the usual way this starts.The water molds need saturated soil to move, so drainage is the primary control and it is set at planting: a low mound or berm with only the uppermost roots covered, positive grade away from the base, the graft union held at least six inches above finished grade per UF/IFAS, mulch pulled about a foot back from the trunk, and emitters kept out of the crown zone. Chronic overwatering of young trees is the usual precipitating error. Foliage that yellows and wilts yet fails to recover after irrigation is the reading that separates this from ordinary water stress.

  2. Resistant rootstock

    When you buy, ask for a tree grafted onto a rootstock with tolerance to this rot, such as Carrizo, Swingle, or trifoliate. You keep the navel variety you want and get roots that stand up to it better. It is settled at the nursery and cannot be added later.A tolerant rootstock such as Carrizo, Swingle, or trifoliate adds a layer of protection where the organism is present in the soil. The scion stays the navel you wanted while the root system carries the tolerance, and it sits on top of the siting work rather than substituting for it, since saturated soil still drives infection.

  3. Prune out infection

    If gum is oozing from a dark patch low on the trunk, sort out the watering or drainage first, since the tree cannot recover while the roots stay wet. Then pare the dark dead bark back carefully until you reach a rim of healthy green tissue, and leave the spot open to dry. Uncovering a crown that had been buried sometimes stops it. A bad root case on an established tree is hard to turn around, which is why the planting practices matter so much.Correct the water and soil condition before cutting, since nothing holds while the root zone stays saturated. Pare an active trunk lesion back to a margin of healthy green tissue and leave it exposed to dry; opening a buried crown to the air sometimes arrests extension. Advanced feeder-root rot on an established tree is difficult to reverse, which is the argument for the planting practices carrying the weight.

No spray for this one. Prevention is the control.

Citrus canker
D · 03
Symptoms Canker makes raised, rough, tan spots, often ringed with yellow and looking a bit oily at the edges, on leaves, twigs, and the skin of the fruit. The spots come through both sides of the leaf and feel bumpy. Bad cases drop leaves and mark the fruit. It is mostly a problem in warm, wet, windy places like the Gulf Coast.Raised, corky, tan lesions with a water-soaked or oily margin and often a yellow halo, appearing on leaves, twigs, and fruit rind. Unlike many leaf spots, canker lesions erupt through both leaf surfaces and feel rough and raised. Severe infection causes defoliation, twig dieback, and blemished, sometimes dropping fruit. It is a regulated disease in the Gulf states and is far more of a problem in warm, wet, windy climates than in arid ones. Cause Bacteria spread it through wind-blown rain and on dirty tools and hands. It gets in through tiny wounds, including the tunnels made by leafminers. Warm, rainy, windy weather makes it worse, so it is mainly a humid-climate problem and rarely shows up in dry inland or desert areas.A bacterium (Xanthomonas citri) that spreads in wind-driven rain and on contaminated tools and hands, entering through natural openings and wounds, including leafminer mines. Warm temperatures, frequent rain, and wind (which wounds tissue and drives the bacteria) make it severe; it is largely absent from dry interior and desert climates. Organic treatment There is no cure, only ways to slow it down. In humid regions, copper sprays during the rainy season help prevent new spots, and you should remove badly infected branches and clean your tools. In dry climates you usually do not need to worry about it.Copper-based protectant sprays applied before and during the wet season are the primary backyard tool in canker regions; they reduce the rate of new infections without curing what is already present. Once infection establishes in wood, prune out and dispose of heavily affected material and disinfect tools between trees to limit spread. In arid California and the desert Southwest, where the humid conditions canker requires are largely absent, growers rarely encounter this disease. Prevention Start with certified clean nursery trees. In regions where canker is established, avoid pruning or working around the tree during or after rain, since the bacteria spread in water, and disinfect your cutting tools between each cut. Controlling leafminer on young trees matters because the feeding tunnels create entry points for the bacteria. Where canker is active in your county, follow your state extension's current guidance.Plant certified disease-free stock and choose less-susceptible varieties where canker is established. Avoid working in the canopy when wet, disinfect pruning tools, manage leafminer (whose mines are infection courts) on young trees, and provide good air movement. In regulated areas, follow state guidance, which may include copper programs.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Certified clean stock

    Start with certified disease-free nursery stock, which is where prevention begins in the regions where canker is established. This is a regulated disease in the Gulf states, so where it is active in your county, follow the guidance your state extension is giving.Certified stock is the at-purchase control for a regulated bacterial disease with no cure, and it is the part of the exposure a grower settles outright. Where the disease is under a state program, that program's direction governs what else is required.

  2. Resistant varieties

    Where canker is established, choose a less susceptible type if one is offered for your area. Outside the warm, wet, windy regions this question hardly comes up.Cultivar choice is the second at-purchase lever where the disease is established, chiefly the humid Southeast and Gulf. In dry interior and desert climates canker is largely absent, so it is not what should drive the selection there.

  3. Wet foliage discipline

    Stay out of the tree while it is wet. Do not prune, pick, or brush past the canopy during or right after rain, because the bacteria move in films of water and ride out on your hands and tools. Disinfect your cutting tools between cuts.Wind-driven rain is the natural dispersal route, so working a wet canopy is how a grower adds to it. Confine pruning and handling to dry conditions and disinfect tools between cuts and between trees. This lowers the rate of spread rather than clearing an infection already present.

  4. Airflow spacing

    Give the canopy room for air to move through it. Warm, rainy, windy weather is what drives this disease, and a canopy that dries faster gives the bacteria less time on the leaf.Air movement shortens the wetness periods that let the bacterium enter through natural openings and wounds. Siting and canopy openness are set once and work passively, which counts for most through a warm rainy season.

  5. Garden sanitation

    Once the disease is into the wood, remove and get rid of the badly affected branches, leaves, and fruit, so there is less bacteria on hand to be splashed onto healthy growth. Disinfect your tools between trees. Bag what you collect and keep it inside a quarantine area rather than hauling citrus material out of one. This slows the spread; it does not clear the tree.Removing and destroying heavily affected material lowers the inoculum available to the next wind-driven rain, and disinfecting tools between trees closes a documented transmission route. It is a reduction in spread pressure rather than a cure, since the tree carries the infection whatever comes off it, and disposal stays inside the quarantine boundary where one applies.

  6. Copper fungicide

    In humid regions, copper protectant sprays before and during the wet season are the main backyard tool. They cut the rate of new infection rather than healing the spots already there, so getting them on ahead of wet, windy weather is the point. Copper is hard on fish and other water life, so keep spray and runoff away from ponds, streams, and storm drains, and follow the label rate, since too much copper burns foliage. In arid California and the desert Southwest, growers rarely run into this disease at all.Copper protectants applied before and through the wet season are the primary backyard material in canker regions, reducing the rate of new infection without curing established lesions, so they sit alongside the sanitation and the wet-work discipline rather than in place of them. Follow regional program guidance on timing and materials where one is in force. Copper accumulates at the soil surface and is highly toxic to aquatic life, so limit repeat use across years and hold to the label rate.

No spray for this one. Prevention is the control.

Greasy spot
D · 04
Symptoms The leaves develop yellow splotches on the upper surface and raised, greasy-looking brown or black blisters on the underside, making the leaf look oily. Affected leaves drop early, usually in late winter, which gradually thins out the tree's canopy. This is mainly a humid-climate disease, concentrated in Florida and along the Gulf Coast, and is rarely seen in the arid West.Yellow mottling on the upper leaf surface that develops into greasy-looking, blister-like brown-to-black lesions on the underside, giving the leaf a translucent, oily appearance. Affected leaves drop prematurely, often in late winter, thinning the canopy. On fruit a fine black speckling (greasy spot rind blotch) can appear. It is primarily a problem in the humid Southeast and Gulf, driven by warm, wet, humid conditions. Cause A fungus causes it, growing on the old fallen leaves under the tree and then infecting new leaves in warm, humid, wet weather. The dead leaves on the ground are where it comes from, so it keeps itself going through the litter.Zasmidium citri-griseum, the causal fungus, completes its spore cycle in the layer of decomposing fallen leaves beneath the tree; from that litter, spores are released during warm, humid, wet periods and infect the leaf undersides, with a long latent interval before the characteristic blistering appears. Because the disease regenerates from its own debris, sanitation under the canopy disrupts the cycle. Organic treatment Cleaning up the fallen leaves is the main organic fix. In humid regions with a lot of it, a horticultural oil or copper spray in early summer helps, but remember not to use oil on very hot days. Most trees outside the humid Southeast do not need anything.Sanitation (removing leaf litter) is the core organic control. Where pressure is high in humid regions, a horticultural oil or copper spray timed to early summer reduces infection; oil also helps by suppressing the fungus on leaf surfaces. Observe oil heat limits. Most home trees outside the humid Southeast need no treatment. Prevention Rake up and get rid of the fallen leaves under the tree, since that is where the fungus lives, and that one step helps the most. Good airflow helps too. In dry inland or desert areas you will probably never see it.Rake up and remove fallen leaves under the tree to break the disease cycle, the single most useful cultural step. Promote air movement and avoid prolonged leaf wetness where you can. In dry inland and desert climates the disease is essentially absent and no action is needed.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Garden sanitation

    Rake up the fallen leaves under the tree and get rid of them. The fungus does its spore-making in that decaying litter, so clearing it away takes out the source of the next round of infection. This single step helps more than anything else you can do here.The fungus completes its spore cycle in the layer of decomposing fallen leaves beneath the tree, so removing that litter attacks the inoculum source directly and is the foundation the rest of the response sits on. Because the disease regenerates from its own debris, sanitation disrupts the cycle rather than merely tidying up.

  2. Airflow spacing

    Give the canopy room for air to move through it. Infection happens during warm, humid, wet stretches, and a canopy that dries faster gives the fungus less of an opening.Air movement works against the warm, humid, wet conditions the spores need to infect the leaf undersides. It is a passive lever set by siting and canopy openness, and it earns its keep through a long warm rainy season.

  3. Copper fungicide

    In the humid Southeast and along the Gulf, where this turns up every year, a copper spray timed to early summer cuts down on infection. Most trees outside those regions need nothing, and in dry inland or desert areas the disease is essentially absent. Copper is toxic to fish, builds up in the soil, and can burn foliage above the label rate, so follow the label and keep spray and runoff out of drains and waterways.Copper applied in early summer, ahead of the long latent interval before the blistering shows, reduces infection where humid-region pressure warrants it, with litter sanitation still doing the base work. It is unwarranted in arid inland and desert citrus areas. Copper accumulates at the soil surface and is highly toxic to aquatic life, so limit repeat use across years and hold to the label rate.

No spray for this one. Prevention is the control.

Sooty mold
D · 05
Symptoms You will see a black, dusty powder covering the leaves and sometimes the fruit; it wipes off and does not actually damage the tree tissue underneath. This is sooty mold, and it grows on the sticky droppings of sap-sucking insects like aphids, scale, or whitefly feeding above. Finding it is a cue to look for the insect that is producing the honeydew.Honeydew secreted by sap-sucking insects colonizes leaf surfaces as a black, powdery-sooty layer on leaves, twigs, and fruit; it can be rubbed off, leaving the tissue beneath undamaged. The mold itself does not infect the tree, but heavy deposits shade the leaf and blemish the rind, and the presence of sooty mold is a reliable indicator that aphids, soft scale, mealybugs, or whitefly are active on the tree. Cause The black mold grows on the sweet honeydew that sap-sucking insects leave behind. So sooty mold really means you have one of those insects feeding on the tree, and ants often make it worse by protecting them.Saprophytic fungi colonize the sugary honeydew excreted by aphids, soft scale, mealybugs, or whitefly. The presence of sooty mold is therefore a symptom of an insect infestation, and ants tending those insects make it worse by protecting them from predators. Organic treatment Treat the insect causing it with horticultural oil or insecticidal soap, and keep ants away. The mold already there can be rinsed or wiped off and will fade once the stickiness stops. Do not use oil on very hot days.Treat the insect, not the mold: horticultural oil or insecticidal soap on the honeydew producer, plus ant control, resolves both. Existing mold can be hosed or wiped off and will weather away once the honeydew stops. Observe oil heat limits. Prevention Get rid of the insect that is making the honeydew (aphids, scale, and so on) and keep ants out, and the mold will have nothing to grow on. You do not need to treat the mold by itself.Control the underlying honeydew producer (aphids, scale, mealybug, or whitefly) and manage ants, and the mold has nothing to grow on. There is no need to treat the mold itself directly.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Ant exclusion

    Sooty mold is not a fungus to go after directly. The black film grows on honeydew, the sticky waste of sap-sucking insects such as aphids, soft scale, mealybugs, or whitefly feeding above it, so the fix starts with those insects. Ants are what keeps them going: they harvest the honeydew and chase off the predators and parasites that would otherwise eat the producers. Find the ant trail on the trunk and shut it down. Wrap the trunk with heavy paper, duct tape, or fabric tree wrap and put the sticky material on that wrap rather than straight onto bark, which it can injure, then check for branches touching the ground, a wall, or another plant, since ants use those to get around the band. What is already on the leaves rubs off, and it weathers away once the honeydew stops.The mold colonizes honeydew rather than plant tissue, so control begins with the honeydew producer and not with the fungus; there is no call for a fungicide against the mold itself. Ant tending sustains those producers by keeping their natural enemies off them, so exclusion acts on the mold's food supply upstream. Per UC IPM the sticky material goes on a collar of heavy paper, duct tape, or fabric tree wrap rather than on bare bark, and the branch bridges to soil, wall, or adjacent plants close in the same pass, since a band with a route around it changes little. Expect a lag: a colony established before the band went on comes down slowly, and the existing coating weathers off rather than being cured.

No spray for this one. Prevention is the control.

Brown rot of fruit
D · 06
Symptoms Brown rot is a firm tan rot on fruit, almost always on the low-hanging fruit near the ground, often with a strong smell. It shows up on ripe fruit in cool, wet fall and winter weather. The clue is that it is the bottom fruit that rots, because the disease splashes up from the soil.A firm, leathery, light-brown decay on fruit hanging low in the canopy, usually within a few feet of the ground, often with a pungent odor and, in humid weather, a white mold on the surface. It typically appears on the rind of mature fruit during cool, wet fall and winter weather and can continue to rot fruit in storage. The low position on the tree is the giveaway, since the fungus splashes up from the soil. Cause The same kind of soil water-mold that causes trunk rot splashes up onto low fruit when it rains, especially in cool wet weather. Fruit and branches hanging near the ground are the ones that get it.Soil-borne Phytophthora species splash onto low fruit during rain, infecting the rind. Cool, wet weather and fruit or skirt foliage close to the ground create the conditions; the same water molds that cause foot rot are responsible here, attacking fruit instead of trunk. Organic treatment Pick off and throw away any rotted fruit right away so it does not spread to stored fruit. In wet-winter areas where it keeps coming back, a copper spray on the lower fruit before the rains helps. Keeping the low branches trimmed and mulching are the most dependable fixes.Remove and dispose of rotted fruit promptly so it does not spread in storage. Where brown rot recurs in wet-winter regions, a copper spray to the lower canopy and fruit before the rainy season is the standard preventive. Skirting and mulching remain the most reliable cultural controls. Prevention Trim the lowest branches so no fruit or leaves hang within about two feet of the ground, add mulch to cut down on splashing, and pick the low fruit early. The same good drainage that prevents trunk rot helps here too. In areas with dry falls it is uncommon.Skirt-prune the tree so no foliage or fruit hangs within about two feet of the ground, mulch to reduce splash, and harvest low fruit promptly. Good drainage (the same practice that prevents foot rot) reduces the inoculum. In dry-fall climates the disease is uncommon.
The control ladder

The ladder troubleshoots from the gentlest solution to the strongest. Start with the gentlest option and only move on when and if it doesn't work.

  1. Improve drainage

    The soil water mold behind this rot builds up in ground that stays wet, so drainage under and around the tree leaves less of it there to be thrown onto the fruit when it rains. In areas with dry falls the disease is uncommon to begin with.Drainage lowers the inoculum available to splash, since the organism is soil-borne and its numbers track how wet the ground stays. It acts on the source rather than on the fruit, and it counts for most in wet-winter regions; where fall and winter stay dry the disease is uncommon.

  2. Splash barrier mulch

    Lay mulch under the tree to cut down on splashing. The rot reaches the fruit when rain throws soil up onto it, so a layer between the soil and the low-hanging fruit takes away the route.Mulch interrupts the splash pathway from soil to low-hanging rind, which is the transmission step this disease depends on. It goes down ahead of the cool wet season rather than in response to symptoms, and it is among the more dependable cultural controls here.

  3. Prompt harvest

    Pick the low-hanging fruit early. Mature fruit near the ground is what this rot takes, so getting it off the tree before the cool wet weather arrives removes the target.Harvesting low fruit promptly takes mature, susceptible rind out of the splash zone ahead of the cool, wet fall and winter period when infection occurs. The low position on the tree is both the diagnostic clue and where this step applies.

  4. Garden sanitation

    Pick off and throw away any rotted fruit right away rather than leaving it on the tree or lying underneath. The decay carries on in storage, so a rotted fruit put away with the sound ones can spread it there.Prompt removal and disposal of rotted fruit limits carryover, since the decay continues in storage and one infected fruit put away with sound ones extends it. Take the culls out of the planting rather than leaving them under the canopy.

  5. Copper fungicide

    Where brown rot keeps coming back in a wet-winter area, a copper spray on the lower canopy and the low fruit before the rains start is the standard preventive. It protects rather than cures, so getting the timing ahead of the wet weather is what makes it work. Copper is toxic to fish, builds up in the soil, and can burn foliage above the label rate, so follow the label and keep spray and runoff out of drains and waterways.A copper application to the lower canopy and fruit ahead of the rainy season is the accepted preventive where the disease recurs in wet-winter regions; it is protective, so it has to precede the infection period to buy anything. The cultural steps stay the dependable part of the response. Mind copper's soil accumulation and aquatic toxicity, and hold to the label rate.

No spray for this one. Prevention is the control.

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Where to plant next year

Crop rotation

Rotation does not apply to a permanent tree like an orange. The one thing to know: if you remove an old citrus tree, avoid planting a replacement in the identical spot. The old root zone can harbor pathogens and depleted soil chemistry that put a new tree under immediate stress. Give a replacement tree a fresh location a few feet away if your space allows.Rotation is not applicable to a permanent tree crop. The one related consideration is citrus replant problems: when removing an old citrus and planting a new one in the same spot, soil-borne issues and residual pathogens can set back the replacement, so it is best to replant in fresh ground, improve and rest the old site, or choose a tolerant rootstock if replanting in place is unavoidable.

Avoid following
N/A for oranges. Rotation is for vegetables you replant each year. An orange tree is permanent and lives in the same spot for many years, so there is nothing to rotate.N/A. Crop rotation does not apply to a navel orange, which is a permanent tree that occupies the same ground for decades rather than an annual replanted each season. There is no rotational sequence to manage.
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Methodology & sources

Every date, temperature, spacing, and recommendation on this page is sourced from university cooperative extension publications, peer-reviewed agricultural research, NOAA climate data, and direct extension calendars. Where claims are softer (traditional gardening wisdom not formally documented), we say so.

Research-backed Documented in cooperative extension publications or peer-reviewed research
Well-grounded A known agronomic principle, but not formally tested for this specific pair
Traditional Time-tested gardening wisdom, limited formal research support
Last reviewed
June 12, 2026
Data version
crops_data_final · v1.0 · schema 2.9
Sources cited on this page
16 publications
Verified entries
Companion-planting claims tagged inline · zone dates verified against 5+ extensions
See all sources cited on this page
  • University of Minnesota Extension umn_ext
  • University of Maryland Extension umd_ext
  • Cornell Cooperative Extension cornell_ext
  • Iowa State University Extension iastate_ext
  • Michigan State University Extension msu_ext
  • NC State Extension ncsu_ext
  • Penn State Extension psu_ext
  • U. of Illinois Urbana-Champaign Extension uiuc_ext
  • UC Davis Postharvest Center ucd_postharvest
  • Texas A&M AgriLife Extension tamu_agrilife
  • Virginia Cooperative Extension 426-331 vce_426_331
  • Piedmont Master Gardeners piedmont_mg
  • UGA Vegetable Garden Calendar uga_calendar
  • Clemson Home & Garden Information Center clemson_hgic
  • UC IPM Statewide IPM Program uc_ipm
  • NOAA 1991-2020 Climate Normals noaa_normals

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Vol. 004 · Orange (Navel) · plant.lifestyle