Pests
Symptoms Cherries that look normal on the outside but have a small white maggot (a grub) inside, usually near the pit, with brown mushy flesh around it. You often do not see it until you cut or bite a cherry. It shows up as the fruit turns from pale to a pink-blush color.Cherries that look fine outside but hide a small white maggot inside, often near the pit, with the flesh browning around it. Infested fruit may soften or show a tiny egg-laying dimple. Damage appears as the fruit colors from straw to salmon-blush and worsens toward harvest. Cause A small fly called the western cherry fruit fly. It spends winter in the soil, comes out in late spring, and lays eggs under the skin of cherries once they start to color. The eggs hatch into the maggots you find inside. There is just one round a year, and green fruit is safe, so the danger starts at color change.The western cherry fruit fly (Rhagoletis indifferens), a small fly with banded wings. Pupae overwinter in the soil; adults emerge from late spring, and after a 5-to-7-day maturation the females lay eggs just under the skin of coloring fruit. There is one generation a year, and green fruit is safe, so timing tracks the color change. Organic treatment Once the maggots are inside, no spray reaches them. The fixes are cleanup and timing: pick every cherry promptly (do not leave any), pick up and destroy fallen fruit so the grubs cannot reach the soil, and put landscape fabric or thick mulch under the tree so they cannot burrow in. A yellow sticky trap put up in mid-May tells you when the flies arrive so you can spray an organic product at the right moment.There is no rescue once maggots are inside the fruit. The backyard controls are sanitation and timing: pick all fruit promptly and completely (leave none to drop), gather and destroy dropped cherries so larvae cannot reach the soil, and lay landscape fabric or dense mulch under the tree to block pupation. Yellow sticky traps from mid-May time any organic spray to 5 to 7 days after the first fly is caught. Prevention Cleanup is the main thing: never leave wormy or fallen cherries on the ground, because each maggot that gets into the soil becomes next year's fly. Picking the tree clean every year and keeping the ground tidy keeps the numbers down.Sanitation is the backbone: never let infested or dropped fruit sit, since each maggot that reaches the soil is next year's fly. Prompt, complete harvest and a clean orchard floor steadily lower pressure. A single isolated tree picked clean every year can stay nearly fly-free.
Symptoms Ripe cherries that go soft, dimpled, and leaky fast, with tiny white maggots inside, and fruit that ferments and smells sour on the tree. The difference from ordinary fruit flies is that this pest attacks whole, undamaged ripe cherries.Soft, sunken, leaking spots on ripe and ripening fruit, with tiny white larvae inside that collapse the flesh within a day or two; fruit ferments and sours on the tree. Unlike common vinegar flies, this one attacks SOUND, intact ripe fruit, not just damaged fruit. Cause A small invasive fly called spotted wing drosophila. Unlike normal fruit flies, the female can cut into whole, healthy ripe cherries to lay her eggs, which hatch into the maggots inside. It multiplies very fast, so it gets worse the longer ripe fruit hangs.Spotted wing drosophila (Drosophila suzukii), an invasive vinegar fly whose females have a saw-like ovipositor that cuts into intact ripe fruit to lay eggs. It builds explosively, completing a generation in as little as a week, so pressure climbs steeply through the harvest window. Organic treatment Picking is the control: harvest ripe cherries every couple of days, remove any overripe or fallen fruit, and get the crop into the fridge quickly, since cold stops the maggots. Fine netting and quick, complete picking are the practical home tools.Harvest is the control: pick ripe fruit promptly and completely, removing culls and any overripe or dropped cherries, and refrigerate the crop right away (cold stops the larvae). Pick every two to three days during ripening. Fine netting and prompt clean-picking are the practical backyard tools; traps with apple-cider-vinegar bait track activity. Prevention Keep ahead of it by never leaving ripe or rotting cherries on the tree or ground, picking often, and chilling the fruit right away. It uses lots of other plants too, so keeping your whole yard's ripe fruit picked up helps.Lower pressure by never leaving ripe or rotting fruit on the tree or ground, picking on a tight schedule, and chilling fruit immediately. Sanitation across the neighborhood matters, since the fly uses many wild and garden hosts.
Symptoms Ripe cherries pecked, half-eaten, or gone, sometimes the whole crop in a day or two, with just pits and torn skins left behind. Robins, starlings, waxwings, and jays are the usual culprits and will clean off an unprotected tree.Ripe and ripening cherries pecked, partly eaten, or stripped entirely, often within a day or two of color, with pits and torn skins left on the spurs. Robins, starlings, waxwings, and jays can take the whole crop of an unprotected tree, working the top and outside first. Cause Birds, which zero in on cherries as they ripen. A ripe cherry tree is a magnet, and a flock can clear it faster than any bug. Light-colored kinds like Rainier and small open trees get hit the worst.Fruit-eating birds, which key in on cherries as they color. A ripe cherry tree is one of the most attractive food sources in the yard, and a flock can strip it faster than any insect pest. Yellow cultivars like Rainier and small trees in open settings are hit hardest. Organic treatment Netting is really the only thing that works: cover the whole tree with fine bird netting as the cherries start to color, and tuck it in at the bottom so birds cannot sneak under. This is the main reason to keep a cherry tree small (on a dwarfing rootstock) so you can actually cover it. Shiny tape and scare balloons help for a little while but birds get used to them.Netting is the only reliable backyard control: drape fine bird netting over the whole canopy as the fruit begins to color, securing it at the bottom so birds cannot get under. This is the single biggest reason to keep a cherry small (a dwarfing rootstock) so it can actually be netted. Scare devices (reflective tape, flash tape, balloons) help briefly but birds soon ignore them. Prevention Plan to net the tree from the start: pick a dwarfing rootstock so the grown tree is small enough to cover, and put the net on as soon as the cherries start coloring, not after the birds show up. Nothing else reliably keeps them off.Plan for netting before you plant by choosing a size-controlling rootstock so the mature tree can be covered. Net early, at first color, not after birds have found the tree, and secure the skirt. There is no substitute for physically excluding them.
Symptoms Clusters of shiny black aphids (tiny soft insects) on the tips of new spring growth, curling and twisting the young leaves, with a sticky coating below that turns black and moldy. It is worst on young trees and mainly stunts new growth rather than ruining fruit.Dense colonies of shiny black aphids on the tips of new spring shoots, tightly curling and twisting the young leaves, with sticky honeydew below that blackens into sooty mold. Heaviest on vigorous young trees; it slows shoot growth but rarely harms fruit directly. Cause A small black insect called the black cherry aphid. Its eggs overwinter on the tree and the young hatch out to feed on the soft new spring growth. The numbers usually drop on their own by midsummer as the shoots toughen and ladybugs and other helpers move in.The black cherry aphid (Myzus cerasi). It overwinters as eggs on the tree and explodes on the tender spring flush, feeding on sap; populations crash by midsummer as the shoots harden and natural enemies build up. Organic treatment Often you can leave it alone, since ladybugs and other helpers clear it by midsummer. On a young tree that is badly hit, blast the colonies off with a hose, or spray the curled tips with insecticidal soap or horticultural oil. Do not over-fertilize, since lush new growth is what the aphids love.Often no action is needed, since beneficials clean it up by midsummer. For a heavy infestation on a young tree, a strong jet of water knocks colonies off, or insecticidal soap or horticultural oil applied to the curled tips works; protect the ladybugs and lacewings that do most of the control. Avoid high-nitrogen feeding, which fuels the soft growth aphids prefer. Prevention Avoid heavy feeding that pushes the soft growth aphids love, welcome ladybugs and lacewings, and do not panic over the spring leaf-curl, which usually does not hurt the cherries. A dormant oil spray in late winter cuts down the overwintering eggs.Keep trees vigorous but not over-fed (high nitrogen invites aphids), encourage beneficial insects, and tolerate the early-season curl, which rarely affects the crop. A dormant oil spray reduces overwintering eggs where the pest is chronic.
Symptoms Sticky gum mixed with what looks like wet sawdust (frass) at the bottom of the trunk or on the lower branches, usually on a wound or crack. The grubs tunnel under the bark, and a young tree with several can be girdled and weakened. The wounds also let in disease.Gummy ooze mixed with sawdust-like frass at the base of the trunk or on the lower scaffolds, centered on wounds, the graft, or bark cracks. Larvae tunnel in the inner bark; repeated attacks weaken or girdle a young tree, and the wounds also open the door to bacterial canker. Cause Several borers (the grubs of certain moths and beetles), mainly the peachtree borer near the soil line and the American plum borer on wounded bark. They tunnel under the bark of stressed or injured cherry trees, getting in through sunburned bark, canker, and mower wounds.Clearwing moth and beetle borers, chiefly the peachtree borer (Synanthedon exitiosa) at the crown and the American plum borer on wounded bark, whose larvae tunnel the inner bark of stressed or injured stone-fruit trees. Sunscald, canker, and mechanical wounds are the entry points. Organic treatment No spray reaches the grubs once they are inside. Where you can find the holes marked by gum and frass, dig the grubs out with a stiff wire. The better fix is to stop giving them wounds: keep mowers and string trimmers away from the trunk, paint the lower trunk white to prevent sunburn, make clean pruning cuts, and keep the tree healthy.There is no spray once larvae are tunneling inside. Where you can find the entry holes by the gum and frass, kill the larvae with a thin wire (worming). The durable control is to prevent the wounds they need: keep mowers and trimmers off the trunk, paint the lower trunk white to prevent sunscald, prune cleanly, and keep the tree vigorous. Prevention Keep the trunk free of wounds: white trunk paint stops the sunburn cracks borers enter, keep mowers away, make clean cuts, and keep the tree healthy. Check the base of the trunk each late summer for fresh gum so you catch them early.Protect the trunk from injury and sunscald (a white trunk paint helps), prune cleanly to avoid leaving stubs and torn bark, and keep the tree vigorous and free of bacterial canker, since borers and canker feed on the same wounds. Inspect the trunk base each late summer for fresh gum.
Diseases
Symptoms At bloom, flowers go limp and brown and small gummy dead patches form on the nearby spurs. As cherries ripen, brown spots appear and spread quickly, sometimes rotting a whole fruit in a day or two in warm, wet weather, with a dusty tan fuzz on top. Rotted fruit shrivels into a hard mummy that hangs on. Split cherries rot the fastest.At bloom, infected blossoms wilt and brown and the infection runs into the spur to form a small gummy canker. As fruit ripens, firm brown spots appear and spread fast, rotting a whole cherry within a day or two in warm, wet weather, with a dusty tan spore mass on the surface. Rotted fruit dries into a clinging mummy. Cracked fruit is especially vulnerable. Cause A fungus called Monilinia. It survives winter in dried mummy fruit and dead twig patches, then releases spores at bloom that infect the flowers, which later cause the fruit to rot. Warm, wet weather makes it spread fast, and a split or wounded cherry rots first.The fungus Monilinia (M. fructicola and M. laxa). It overwinters in mummies and twig cankers; spores at bloom infect flowers, and those infections later seed the fruit rot. Warm, humid, wet weather drives it, and any wound, especially a rain crack, is an open door. Organic treatment Cleanup is the main control: take off and destroy every dried mummy from the tree and ground and prune out the gummy dead twig patches, which hold the spores. If bloom is wet, an organic-approved spray at bloom helps protect the flowers. Pick on time, handle gently, throw out any rotting cherry right away, and grow crack-resistant kinds so fewer split.Sanitation is the core control: remove and destroy every mummy from the tree and ground and prune out gummy twig cankers, since these are the spore sources. In a wet bloom, an organic-approved bloom-time fungicide reduces blossom blight. Pick promptly, handle gently, remove any rotting fruit at once, and choose crack-resistant cultivars to cut the wounds that let it in. Prevention Cleaning up all year prevents most of it: never leave dried mummies over winter, prune so the tree is open and the fruit dries fast after rain, pick on time, and prevent cracking (keep watering even, pick crack-resistant kinds), since split cherries rot first.Year-round sanitation prevents most loss: never leave mummies over winter, keep the canopy open with pruning so fruit dries fast after rain, harvest promptly, and prevent the fruit cracks that invite infection by keeping moisture even and choosing tolerant cultivars.
Symptoms Sunken, dark, gummy patches (cankers) on the trunk and branches that ooze amber sap, often killing the branch above them. In spring, flowers and buds may blacken and die, and some buds never open. It is the most serious sweet cherry disease and can kill a young tree.Sunken, dark, gummy cankers on trunk, scaffolds, and spurs that ooze amber gum, often girdling and killing limbs; in spring, blossoms and spurs blast (blacken and die) and dormant buds fail to open. It is the single most serious disease of sweet cherry and can kill a young tree outright. Cause A bacterium (a microscopic organism) called Pseudomonas syringae. It gets in through wounds, leaf scars, and frost damage during cool, wet weather, and is worse on stressed trees, those in wet soil, hit by frost, or pushed with too much nitrogen.The bacterium Pseudomonas syringae. It infects through wounds, leaf scars, and frost-injured tissue in cool, wet spring and fall weather, and is worsened by anything that stresses the tree: poor drainage, ring nematodes, frost, and high-nitrogen soft growth. Organic treatment There is no cure once it sets in. The approach is prevention: cut out the cankered wood well below the dead patch during dry summer weather (not in wet spring), clean your tools between cuts, and pull out a badly infected young tree. Keep the tree healthy and unstressed; copper sprays only help a little.There is no cure once a tree is infected. Management is preventive: cut out cankered wood well below the canker in dry summer weather (not in wet spring), disinfecting tools between cuts, and remove badly infected young trees. Keep the tree unstressed; copper sprays give only partial protection and resistance is common. Prevention Prevention is everything: plant where the soil drains well, avoid frosty low spots and trunk wounds, paint the trunk white to prevent sunburn cracks, prune only in dry summer weather, and do not over-feed. A healthy, unstressed tree on good ground shrugs it off best.Prevention is everything: plant on well-drained ground, choose a tolerant rootstock, avoid frost-pocket sites and trunk wounds, paint the trunk white against sunscald cracks, prune only in dry summer weather, and never push soft growth with late nitrogen. A vigorous, unstressed, well-drained tree resists it best.
Symptoms Small purple-brown spots on the leaves in late spring, with the spots sometimes dropping out to leave little holes. Infected leaves turn yellow and fall, and a bad case can strip the tree of leaves by midsummer, which weakens it and the next crop.Small purple-to-brown spots on the upper leaf surface in late spring; the spotted tissue may drop out leaving a shot-hole look, and infected leaves yellow and fall. Heavy infection defoliates the tree by midsummer, weakening it, reducing the crop, and leaving it prone to winter injury. Cause A fungus called Blumeriella jaapii. It spends winter in fallen leaves and infects the new leaves during warm, wet spring weather, building up over a wet season until the tree drops its leaves early.The fungus Blumeriella jaapii. It overwinters in fallen leaves and infects new leaves in warm, wet spring and early-summer weather; repeated cycles through a wet season drive the defoliation. Organic treatment Rake up and destroy the fallen leaves in fall, which is the most useful thing you can do, since the fungus overwinters in them. Keep the tree open so leaves dry fast, and in wet areas an organic-approved spray starting after the petals fall protects the new leaves.Rake and destroy fallen leaves in autumn to remove the overwintering source, the single most useful home step. Keep the canopy open for fast drying, and in wet regions an organic-approved fungicide program from petal fall protects the new leaves. Keeping the tree from defoliating preserves its winter hardiness. Prevention The main thing is raking up and destroying fallen leaves in fall, where the fungus waits out winter. Pruning for good airflow so leaves dry quickly helps too, and a spray program is most important in wet springs.Autumn leaf cleanup is the backbone, since the fungus overwinters in fallen leaves. Good airflow from pruning and prompt drying after rain reduce infection, and a protective spray program matters most in wet springs.
Symptoms A slow decline over a few years: the cherries on affected branches stay small, pale, and bitter with a leathery skin, and one branch at a time weakens and dies while the rest of the tree still looks okay. There is no cure, and it spreads to nearby trees.A slow decline over a few years: fruit on affected limbs stays small, pale, and bitter with a leathery buckskin look and short stems, leaves may bronze, and individual scaffolds decline and die while the rest of the tree looks normal. It is incurable and spreads to nearby trees. Cause A tiny bacterium-like organism spread by small insects called leafhoppers and through connected roots. It also hides in other infected stone-fruit trees and some weeds. Once a tree has it, it cannot be cured, only removed so it does not spread.A phytoplasma (a bacterium-like organism) spread by leafhoppers and through root grafts. It also lives in nearby infected stone fruit and certain weeds, and once a tree is infected it cannot be cured, only removed to protect others. Organic treatment There is no cure. The fix is to remove it: have a suspect tree tested, then promptly take out and destroy any confirmed-infected tree, roots and all, so it does not spread to your other trees. Clearing nearby weeds and wild cherries helps too.There is no treatment. The control is removal: test a suspect tree, and promptly remove and destroy confirmed-infected trees (including the roots) to stop spread to neighbors. Manage leafhoppers and clear nearby weed and wild-cherry reservoirs. Prevention Prevention means starting with healthy nursery trees, promptly removing infected trees nearby, controlling the leafhoppers that carry it, and clearing weeds and wild cherries that host it. Do not plant a new cherry right next to one you lost to this disease.Prevention rests on clean planting stock, prompt removal of infected trees in the area, leafhopper management, and clearing the weed and wild-Prunus hosts that harbor it. Do not replant a new cherry next to a tree lost to X-disease without removing the source.
