Pests
Symptoms Cherries that look normal on the outside but have a small white maggot (a grub) inside, near the pit, with brown mushy flesh around it. You often do not see it until you cut or bite one. It starts as the fruit begins to color.Cherries that look fine outside but hide a small white maggot inside, near the pit, with the flesh browning around it. Infested fruit softens and may show a tiny egg-laying dimple; damage worsens as the fruit colors toward harvest. Cause Small flies called cherry fruit flies. They spend winter in the soil, come out in late spring, and lay 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.Cherry fruit flies, chiefly the eastern cherry fruit fly (Rhagoletis cingulata) and black cherry fruit fly (R. fausta) across the sour cherry belt, and the western cherry fruit fly (R. indifferens) in the West. Pupae overwinter in the soil; adults emerge in late spring, and after a short maturation the females lay eggs just under the skin of coloring fruit. 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, 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 in mid-spring tells you when the flies arrive so you can spray 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, 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-spring time any organic spray to a few 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 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 well-picked tree 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. 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, remove culls and any overripe or dropped cherries, and refrigerate the crop right away, since cold stops the larvae. Pick every two to three days during ripening. Fine netting and prompt clean-picking are the practical backyard tools; apple-cider-vinegar traps 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. Neighborhood sanitation matters, since the fly uses many wild and garden hosts.
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 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 on 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 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. 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. The good news is that a sour cherry is naturally a small tree, so it is much easier to cover than a big sweet cherry.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. Sour cherry has one built-in advantage: it is naturally small, so it is far easier to net than a full-size sweet cherry. 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. A small sour cherry, especially a dwarf like North Star, is easy to cover. 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. A naturally small sour cherry (or a dwarf North Star) is easy to net. Scare devices (reflective tape, balloons) help briefly but birds soon ignore them. Prevention Plan to net the tree; a sour cherry is small enough to cover easily. Put the net on as soon as the cherries start coloring, not after the birds show up, and tuck it in at the bottom. Nothing else reliably keeps them off.Plan for netting from the start; the small stature of sour cherry makes this easy. Net early, at first color, not after birds have found the tree, and secure the skirt. There is no substitute for physically excluding them.
Diseases
Symptoms Small purple-brown spots on the leaves from late spring, with spots sometimes dropping out to leave little holes. Infected leaves turn yellow and fall, and a bad case strips the tree of leaves by midsummer. This is the most serious sour cherry disease, and Montmorency is hit especially hard, dropping leaves after just a few spots. Losing the leaves early weakens the tree and the crop, this year and next.Small purple-to-brown spots on the upper leaf surface from late spring; the spotted tissue may drop out for a shot-hole look, and infected leaves yellow and fall. It is the single most important disease of sour cherry: Montmorency is highly susceptible and drops leaves after only a few lesions, and heavy infection defoliates the tree by midsummer, which shrinks the crop, leaves fruit soft and poorly ripened, weakens winter hardiness, and cuts next year's bloom. 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. Sour cherries, especially Montmorency, catch it easily.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. Montmorency and most sour cherries are highly susceptible. 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 program starting after the petals fall protects the new leaves. Keeping the leaves on the tree protects both the tree and next year's cherries.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 through the season protects the new leaves; commercial orchards spray many times a season on Montmorency. Keeping the tree in leaf preserves its hardiness and next year's crop. 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 and on Montmorency.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 and on susceptible Montmorency.
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 keep the watering even 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 keep moisture even so the fruit does not crack. 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 keep watering even so the fruit does not split, 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.
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. Sour cherry shrugs it off better than sweet cherry, but it can still kill a young or stressed 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. Sour cherry is somewhat more tolerant than sweet cherry, but canker can still kill a young or stressed tree. 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. 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, 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.
