Pests
Symptoms Tiny maggots inside ripe berries, with the fruit going soft and mushy. The adult is a small fly with a spot on each wing.Small white maggots inside ripe and ripening berries; fruit softens, collapses, and leaks when squeezed. The adult is a tiny vinegar-fly-like insect, the male with a dark spot near each wingtip. Late-ripening and fall primocane crops are hit hardest. Cause An invasive fruit fly that lays eggs in good, ripe berries (not just rotten ones), and the maggots feed inside.Spotted-wing drosophila (Drosophila suzukii), an invasive vinegar fly whose females cut into healthy ripe fruit to lay eggs, unlike common fruit flies that use only rotting fruit. It is the major modern blackberry pest and the reason clean, frequent picking now defines a successful patch. Organic treatment Pick ripe berries every day or two and clean up any fallen or overripe ones (seal them in a bag, do not compost). Keep the planting open and airy. A cup of apple cider vinegar makes a simple monitoring trap.Harvest completely and often, every one to two days, so no ripe fruit is left on the cane, and remove and destroy overripe or fallen berries (bag them, do not compost). Open the canopy by pruning and trellising to reduce the cool, humid shelter the fly favors. Fine exclusion netting under 1 mm mesh and apple-cider-vinegar monitoring traps help. Prevention Grow earlier varieties when you can, keep the row open and trellised, and pick often. Clear out wild brambles nearby.Choose early-ripening cultivars to dodge peak fly pressure, keep the planting open and well-trellised, harvest on a tight schedule, and remove nearby wild brambles that host the fly.
Symptoms A swollen, spindle-shaped lump on a new cane, with the cane above it weak or dead. A grub is tunneling inside where the swelling is.A cigar-shaped, spindle-like swelling or gall on a primocane, usually 1 to 3 inches long, with the cane above it weak, stunted, or dead. The gall marks where a larva has tunneled and fed inside the cane, and canes often snap at the swelling. Cause A small beetle whose grub tunnels inside new canes and makes a swollen gall. It is common on blackberries, especially near wild brambles.Red-necked cane borer (Agrilus ruficollis), a small metallic-black beetle with a coppery-red thorax whose larva bores into primocanes and causes the diagnostic gall. It is one of the more common blackberry-specific borers, worse near wild brambles. Organic treatment Cut off and throw away any cane with a swollen gall, cutting below the lump to get the grub. Pick off any beetles you see.Cut out and destroy any cane showing a gall, cutting well below the swelling to remove the larva before it matures, and do this during the dormant season and again through summer as galls appear. Hand-pick the adult beetles. No spray is usually needed in a home planting. Prevention Check new canes for swollen galls and cut them out, and remove wild brambles nearby.Scout primocanes for galls and prune them out promptly, remove wild brambles that harbor the beetle, and keep the planting vigorous so it outgrows light injury.
Symptoms Canes weaken, the leaves redden and wilt, and canes snap off at the base. The crown is tunneled inside. Plants slowly die.Whole canes weaken, leaves redden and wilt, and canes break off easily at the base; the crown and lower cane show tunneling and sawdust-like frass. Plants decline over two seasons and can die. A clearwing moth that mimics a yellowjacket is the adult. Cause A wasp-mimic moth whose grubs tunnel into the crown and base of the canes over two years, killing the plant from below.Raspberry crown borer (Pennisetia marginata), a clearwing moth whose larvae bore into the crown and lower canes of blackberry and raspberry over a two-year life cycle, destroying the base of the plant. Organic treatment Dig out and destroy badly infested plants, because the grubs are hidden inside the crown. Start new plantings with healthy plants on clean ground.Dig and destroy infested crowns, since the larvae are protected inside and hard to reach. Starting with clean nursery stock on a fresh site is the most effective control; keep plants vigorous so they outgrow light injury. Prevention Buy healthy plants, choose a spot with no old brambles, and dig out any plants that get infested.Plant certified, borer-free stock on ground without a recent bramble history, remove wild brambles nearby, and remove and destroy infested crowns to break the two-year cycle.
Symptoms Berries ripen unevenly, with some little bumps staying hard and red while the rest turns black. Shield-shaped green or brown bugs are feeding on the fruit.Individual drupelets on a berry fail to color and stay hard, red, and sour while the rest ripens black, giving a lumpy, unevenly ripened fruit. Shield-shaped green or brown bugs feed on the developing berries, and a musty odor may cling to picked fruit. Cause Shield-shaped bugs that pierce the developing berries and kill little segments, so the fruit ripens lumpy and uneven. They are worse near weeds and in warm regions.Several stink bug species (including the brown marmorated stink bug) pierce developing drupelets to feed, killing individual segments so the berry never ripens evenly. Pressure is highest near weedy edges and in the warm South. Organic treatment Pick the bugs off into soapy water, mow weedy edges, and harvest often. Netting the fruit helps if there are a lot of them.Hand-pick bugs into soapy water, keep weedy borders mowed to reduce shelter, and harvest promptly. Row-edge trap plantings and exclusion netting help where pressure is heavy. Prevention Keep weeds down around the planting, check the berries as they form, and pick often.Mow and clean up weedy field margins, scout the planting during fruit set, and harvest on a tight schedule so fruit does not linger.
Symptoms Leaves chewed down to lace and berries nibbled, by shiny green-and-copper beetles that feed in groups on warm days.Leaves skeletonized to a lace of veins, and ripening berries chewed, often by clusters of metallic green-and-copper beetles feeding in the open on warm days from early to midsummer. Cause An introduced beetle whose adults eat the leaves and berries; its grubs live in lawns nearby.Japanese beetle (Popillia japonica), an introduced scarab whose adults feed on blackberry foliage and fruit; grubs develop in nearby turf. Organic treatment Knock the beetles into a jar of soapy water in the morning while they are slow. Do not use the bag traps, which attract even more. Net the fruit as it ripens.Hand-pick beetles into soapy water in the cool morning when they are sluggish, the most effective home control. Skip pheromone traps, which draw in more beetles than they catch. Protect ripening fruit with netting. Prevention Pick beetles off regularly while they are active, and keep plants healthy so they shrug off the damage.Keep plants vigorous, hand-pick consistently during the flight, and manage grubs in adjacent lawn areas if pressure is high.
Symptoms Tiny soft bugs on new shoots and under leaves, sometimes with sticky residue. The bigger risk is the viruses they can spread.Small soft-bodied insects clustered on shoot tips and leaf undersides, sometimes curling new growth and leaving sticky honeydew. Their real danger is spreading the viruses behind blackberry decline, not the feeding itself. Cause Small sap-sucking insects whose main threat is carrying plant viruses from one bramble to another.Several aphid species feed on blackberry sap and can transmit the viruses that build into the crumbly-fruit decline complex over time. Organic treatment Spray them off with water, let ladybugs help, or use insecticidal soap if there are many. Do not over-fertilize.Knock light infestations off with a strong spray of water, support ladybugs and other natural enemies, and use insecticidal soap if needed. Avoid heavy nitrogen, which fuels the soft growth aphids prefer. Prevention Buy certified virus-free plants, pull out wild brambles and any sickly plants nearby, and encourage helpful bugs.Start with certified virus-free plants, remove nearby wild brambles and any virus-symptomatic plants, support beneficial insects, and avoid excess nitrogen.
Diseases
Symptoms Canes are weak, leaves yellow and wilt, and plants die in soggy spots. The roots are brown and rotten.Canes are weak and stunted, leaves yellow or scorch and wilt, and whole canes collapse, worst in low or poorly drained spots. Dug roots are brown to black and rotted, with a reddish-brown discoloration into the crown. Cause A soil disease that rots the roots when the soil stays too wet; a common reason blackberry plantings fail.Soilborne Phytophthora water molds that attack roots in wet, poorly drained soil; a common and damaging cause of blackberry decline, especially on heavy ground and in low spots. Organic treatment You cannot fix rotted roots, so it is all about drainage: plant on raised rows, keep water moving away, and replace dead plants on a drier spot.There is no cure once roots rot, so the response is drainage. Plant on tall raised beds or ridges, divert surface water, and replace dead plants with clean stock on a better-drained site. Prevention Plant on raised rows with good drainage, never let the soil stay soggy, and buy healthy plants.Plant only on well-drained ground or raised beds, choose more tolerant cultivars, never let blackberries sit in saturated soil, and start with disease-free plants.
Symptoms In spring the flower buds open into strange, doubled, wrinkled reddish blossoms in a broom-like cluster instead of normal flowers, and those canes make almost no fruit.In spring, buds burst into a broom-like cluster of distorted, wrinkled, reddish flowers instead of normal blooms, and the shoot below them proliferates into a bunchy witches' broom. The diseased flowers set little or no fruit, and an infected cane is effectively barren. Cause A fungus (called double blossom) that infects the flower buds and makes the deformed blooms. It is the biggest blackberry problem in the humid Southeast, especially near wild brambles.The fungus Cercosporella rubi (rosette, or double blossom), which infects buds and causes the deformed flowers and witches'-broom growth. It is the most serious blackberry disease of the humid Southeast, spread by spores from infected buds to new growth during bloom, and it is worst on erect thorny types near wild brambles. Organic treatment Cut out and destroy any cane with the strange doubled blossoms right away, before it spreads. In the South, mowing the whole planting down after harvest to start fresh canes is a common fix. Remove badly infected plants entirely.Prune out and destroy every cane showing the broom-like distorted bloom as soon as it appears, before its spores spread to healthy canes; in badly hit Southern plantings, mowing the whole planting to the ground after harvest to grow a fresh, disease-free set of primocanes is a standard reset. Rogue out severely infected plants. Prevention Buy disease-free plants, choose resistant varieties, pull out wild brambles nearby, and check the blossoms closely each spring in the South.Start with disease-free stock and plant resistant cultivars (many primocane-fruiting and some thornless erect types are more tolerant), remove nearby wild brambles, keep the planting open and airy, and scout closely at bloom in the Southeast.
Symptoms Small purple spots on the canes that grow into gray, sunken pits with purple edges, plus spots on the leaves.Small purplish spots on young canes that enlarge into gray-centered, purple-bordered pits; spots also appear on leaves and can crack the bark. Severe infections weaken canes and reduce yield, worst in wet springs and crowded plantings. Cause A fungus that lives on old canes and infects new growth in wet weather, leaving sunken spots on the canes and leaves.The fungus Elsinoe veneta (anthracnose), which overwinters on old canes and infects new growth during wet weather. Crowded, over-fertilized rows and overhead watering make it worse. Organic treatment Cut out old and badly spotted canes, keep the planting open and airy, and water at the base, not over the leaves.Prune out and destroy old fruited canes and the most spotted primocanes, open the canopy for air movement, and avoid overhead watering. A dormant lime-sulfur application before bud break helps in bad cases. Prevention Use healthy plants, keep the row open, remove old canes yearly, and water low.Start with clean plants, keep rows narrow and open, prune out spent canes each year, water at the base, and choose resistant cultivars where available.
Symptoms Dark cankers on the canes that make them wilt or snap, and weak or dead fruiting side shoots the next year.Dark brown to purple cankers spread from wounds and leaf nodes, and canes wilt or die back above them, often snapping at the canker. Fruiting laterals on affected canes are weak or fail, and the wilting typically shows the year after infection. Cause Fungi that get into the canes through wounds and crowded growth, causing cankers and weak side shoots.Fungal canker pathogens that enter through pruning wounds and injured or crowded wood; both are worse in dense, wet, over-fertilized plantings. Organic treatment Cut out cankered canes well below the damage, clean your pruners between cuts, and thin the canes so air moves through.Prune out and destroy infected canes well below the canker, disinfecting tools between cuts, and thin canes for air movement. Avoid wounding canes and do not over-fertilize with nitrogen. Prevention Keep the row thin and airy, prune in dry weather, go easy on fertilizer, and remove old fruited canes right after harvest.Keep rows narrow and open, thin to the recommended cane density, prune only in dry weather, avoid excess nitrogen, and remove spent floricanes promptly after harvest.
Symptoms Weak, spindly new shoots in spring with bright orange powder coating the undersides of the leaves. The whole plant is infected for good.In spring, new shoots are spindly, pale, and bunchy, and the undersides of the leaves are covered with bright orange, powdery pustules. Affected plants never recover; the fungus is systemic in the whole plant, and blackberries are especially susceptible. Cause A rust fungus that infects the whole plant for life, especially bad on blackberries and wild brambles.A systemic rust fungus that permanently infects the entire plant, most serious on blackberries and on wild brambles that seed spores into a planting. Organic treatment There is no fixing it. Dig up and destroy any plant showing the orange powder, roots and all, before it spreads. Pull out wild brambles nearby.There is no cure: dig out and destroy infected plants, roots and all, as soon as the orange pustules appear, before they shed spores onto healthy plants. Remove nearby wild brambles that carry it. Prevention Buy healthy plants, check new shoots each spring and remove any infected ones right away, and clear out wild brambles.Start with clean nursery stock, inspect new shoots each spring and rogue out any with orange rust immediately, remove wild brambles, and favor more resistant cultivars where rust is common.
