Blueberry

Birds find ripening fruit and seed before you do. Robins, waxwings, starlings, catbirds, jays, sparrows, finches, blackbirds, and doves all work a garden, and the pressure arrives in a narrow window - the last days before harvest, when sugar rises, color changes, and the crop softens or the grain hardens. A flock can strip a small planting in a day or two, and birds that only peck rather than take whole fruit still leave wounds that rot or draw wasps. Squirrels, chipmunks, and other wildlife usually turn up on the same crop at the same time. This is competition rather than disease: the birds are not harming the plant, and a big tree or a heavy-cropping bush often has enough for everyone - but on a small planting it can be the difference between a harvest and none.

Watch for: Fruit disappearing from the outermost, most exposed parts of the plant first, and from the top of a tree where you cannot reach anyway. Single neat pecks and gouges in ripening fruit, with several fruits sampled rather than one eaten through - the classic sign that it was birds rather than an animal. Heads of grain or seed going visibly lighter and emptier as they ripen, with hulls and chaff scattered underneath. Freshly sown seed vanishing off the surface of a bed before it germinates. Bird traffic in and out of the plant picking up as the crop colors, and birds waiting on nearby wires and branches. Wasps arriving at the pecked and split fruit shortly afterward.

Prevent: Net, and net early. Bird netting draped over a frame or hoops so it stands off the fruit, with the edges closed at ground level, is the only thing that reliably works at harvest scale - and it has to go on before the crop starts to color, because once birds have found the food they are far harder to displace. Keep fruit trees small enough that netting them is actually feasible; that decision gets made years earlier, at planting. Bags of mesh, organza, or paper slipped over individual heads, clusters, or prize fruit protect a small crop without netting the whole plant. Then shorten the exposure: pick promptly and completely rather than leaving ripe fruit hanging as a lure, clear split and dropped fruit that draws birds and wasps alike, and where a crop can finish off the plant, harvest a little early and ripen or dry it under cover. Rake in or cover broadcast seed so it is not lying in plain view.

Treat: There is no treatment once a crop is being taken - only protection and timing, so the answer is to get netting on and to pick what is ready. Reflective tape, flash ribbon, spinners, and decoy predators do work, but only for a few days at a time: birds habituate fast, so move and rotate them and never rely on them as the main defense for a crop you care about. Cut and gather grain or seed heads a little early, at firm dough, and finish drying them under cover instead of leaving them standing for the flocks. Plant a little extra, or a decoy crop the birds prefer, and accept sharing anything that crops heavily. On a wild or foraged patch, fruit going to birds and small mammals is the point of the plant rather than a problem to solve.

The number-one blueberry pest for home growers - a single unnetted bush feeds the whole neighborhood's birds, often faster than you can pick. Net over a frame, closed at ground level, before the berries start to color; reflective tape buys days at best.

A soil-borne water mold (Phytophthora species) that rots feeder roots and, on many plants, the crown at the soil line whenever the ground stays saturated. Rotted roots cannot take up water, so the plant looks drought-stressed even in wet soil: the canopy thins, leaves go small and pale, growth stalls, and dieback works in from the tips over months or years. It is the commonest cause of death in plants that want moisture but cannot tolerate standing water, and it travels in surface water and on tools, boots and moved soil.

Watch for: Wilting, yellowing and stunting that does not improve with watering, a thinning canopy of small pale leaves, and dieback from the shoot tips. Dig and the feeder roots are dark, soft or brittle rather than white and firm, and on many plants the tissue at the base of the stem is discolored under the bark. Worst in low spots, and wherever a downspout, driveway or compacted path drains into the bed.

Prevent: Drainage is the whole defense. Plant on a mound, berm or raised bed in heavy soil, and never in a hollow that holds winter water. Redirect roof and hard-surface runoff away from the planting, water deeply but infrequently so the surface dries between waterings, do not pile mulch against stems, and do not overwater in cold weather when the plant is using little. Use resistant rootstocks or tolerant varieties where they exist for the crop, and never move soil from an infected area.

Treat: Very hard to reverse once established. Improve the drainage immediately, cut watering back, and mulch with coarse material rather than fine, which stays sodden. Remove severely affected plants and correct the site before replanting - and do not put another susceptible plant back into the same wet spot. Phosphonate (phosphite) treatments can suppress it in a valuable specimen, but drainage and siting do far more.

Blueberries' fine surface roots are especially vulnerable to soggy ground, and a bush declines over one or more seasons rather than collapsing outright. Raised beds of pine bark and peat are the standard answer, and Patriot and Reka are tolerant varieties for marginal sites.

An invasive vinegar fly (Drosophila suzukii). Unlike ordinary fruit flies, which need damaged or overripe fruit, the female has a saw-edged ovipositor that cuts into sound, intact, ripening fruit to lay her eggs. The larvae feed inside, so the fruit softens, sinks, weeps and collapses just as you were about to pick it. It has become the dominant pest of soft fruit across the country, and the old rule that fruit flies only bother spoiled fruit no longer applies.

Watch for: Soft, sunken, weeping fruit that collapses under light pressure, and tiny egg-laying scars on otherwise perfect ripening berries. To confirm, crush or float suspect fruit in salt water (1-2 teaspoons per cup) and look for small white maggots floating out. In an apple-cider-vinegar or yeast-sugar trap, the males carry a distinct dark spot at each wingtip.

Prevent: Pick short and often - every two or three days through the ripening window - and remove ALL overripe and dropped fruit, because culls left on the plant or the ground breed the next generation. Cool the harvest to about 35°F promptly, which stops larvae developing in fruit you have already picked. Fine mesh under 1 mm excludes the fly where pressure is high.

Treat: There is no rescue for infested fruit. Control is relentless sanitation plus trap-based monitoring to time any spray: bag or freeze culls rather than leaving them, never drop them on the ground, and use vinegar or yeast-sugar traps to tell you when the flies have arrived. Well-timed targeted sprays such as spinosad are used where pressure is high - use only a product labeled for the crop you are treating, follow the label exactly, and observe its pre-harvest interval.

A three to five day harvest interval is the practical target on blueberries, and dropped fruit under the bush is the breeding source that keeps a population going.

A blueberry-specific fungal disease (Monilinia vaccinii-corymbosi): spring spores infect new shoots and flowers, then infected berries fill with fungus, turn tan, shrivel into hard 'mummies', and drop to overwinter and start the cycle again.

Watch for: Sudden wilting and browning ('shepherd's crook') of new shoots and flower clusters in spring, followed by cream-tan, shriveled, mummified berries at harvest.

Prevent: Rake up and destroy fallen mummies, then bury them under 2 inches of fresh mulch in late winter to block the spring spore stage; choose resistant varieties (Duke) and avoid highly susceptible ones (Bluecrop, Blueray, Jersey) where it's a problem.

Treat: Sanitation is primary - remove mummies and re-mulch every winter. Where severe, a dormant-to-bloom fungicide program timed to the spore release helps; no cure exists once berries mummify.

An aphid-transmitted virus that blights blossoms and scorches leaves in spring; there is no cure, and infected bushes decline and spread the virus to neighbors over time.

Watch for: Sudden blighting of flowers and young shoots and browned, 'scorched' leaves in spring, resembling frost damage but recurring yearly and spreading bush to bush.

Prevent: Buy certified virus-free plants, control aphids (the vector), and remove infected bushes quickly to protect the rest of the planting.

Treat: None - rogue out and destroy infected bushes and manage aphids on the survivors. This is a source-control disease, not a treatable one.

Japanese beetles are metallic green-and-copper beetles about half an inch long that emerge in early summer and feed for six to eight weeks. They feed in aggregating masses - one beetle's feeding releases a scent that draws in more - so a plant goes from untouched to covered in a couple of days. They chew the soft tissue between the leaf veins and leave the veins standing, so the leaf ends up as a brown lace skeleton, and they shred open flowers and sometimes ripening fruit as well. They work the sunniest upper parts of a plant on warm afternoons. The white C-shaped grubs spend the rest of the year in turf and pasture soil eating grass roots, and the adults then fly in from wherever they hatched, which can be some distance away.

Watch for: Clusters of shiny metallic beetles massed together on the upper, sunniest foliage and down inside open blooms, heaviest on warm sunny afternoons from around late June. Leaves reduced to lace, with the veins left intact and the tissue between them gone - unmistakable, and quite different from the ragged chewing of a caterpillar. Ragged, chewed petals and blooms that never open properly. Beetles that let go and drop straight to the ground when you disturb the plant. Feeding damage on ripening fruit, on the plants they also take fruit from. Whole branches going brown and lacy at the top of a plant while the shaded lower growth stays untouched.

Prevent: Hand-picking is genuinely the main defense in a home garden. Go out in the cool of the morning while the beetles are sluggish, hold a tub of soapy water underneath, and knock them in - they drop when disturbed, so most fall straight into it. Do it daily through the flight: because the beetles call each other in, taking them off early stops a plant becoming a beacon. Do not put pheromone or lure traps anywhere near the garden - they demonstrably pull in far more beetles than they catch. And do not count on lawn grub control: milky spore has performed poorly and inconsistently in field trials across most of the US, and treating your own turf does not reduce the adults feeding on your plants, because they fly in from surrounding properties. Where it is practical, row cover or netting through the peak flight excludes them outright. Otherwise riding out the six-to-eight-week wave is a legitimate strategy, since most established plants absorb the damage.

Treat: Persistent morning hand-picking into soapy water is the most effective home control there is, and on a vigorous established plant the damage is usually cosmetic and needs nothing else. Neem deters feeding rather than killing, and has to be reapplied. For heavy pressure, spinosad or a targeted insecticide labeled for the plant will work - but time any spray away from bloom and apply it at dusk to protect bees, and observe the pre-harvest interval on anything you eat. On flowering plants, some gardeners simply shear the blooms off for a couple of weeks and let the plant rebloom once the wave has passed, which removes the lure as well as the damage. Young plants and young trees are the ones worth defending: a mature tree or an established vine tolerates several weeks of leaf loss without lasting harm.

Usually cosmetic on established bushes, and the netting you put up for birds also excludes beetles. Hand-picking is very effective on just a few bushes.

Botrytis cinerea and its relatives - the fuzzy gray-brown mold of cool, wet, humid weather. It blights flowers and buds, rots ripening fruit, and moves into soft, aging, bruised or frost-damaged tissue through the smallest wound, coating whatever it kills in dusty gray spores. It overwinters on dead plant debris, spreads on air currents and by direct contact between touching tissue, and keeps working after harvest, which is why it also ruins fruit and bulbs in storage.

Watch for: Browned, collapsed flowers and buds; soft, water-soaked brown patches on leaves, stems or fruit; and a dusty gray-brown fuzz over the dead tissue. Rot jumping between two pieces of fruit or two petals that touch is the signature, and it often shows up again in the fridge or the storage box days later.

Prevent: Space and prune for airflow, water at the base rather than over the top, and go easy on nitrogen, which produces the soft growth it prefers. Clear dead leaves, spent flowers and rotting fruit at every pass, since that debris is where it overwinters. Handle fruit, buds and bulbs gently, because it enters through bruises, and cure and store anything you keep dry and well ventilated.

Treat: Cut out and destroy infected tissue as soon as it appears, and bag it rather than composting it. Harvest ahead of a prolonged wet spell and store the crop dry and cold. Protective fungicides help through long damp weather, but airflow and sanitation do most of the work.

Two hits on blueberry: blighted blossoms in a wet spring, which costs you fruit before you notice, and soft rot on the ripe berry. Prune for an open bush, keep nitrogen moderate, and pick promptly.

Aphids are small soft-bodied sap-suckers - green, black, gray, pink, or waxy white, and mostly wingless - that gather in dense colonies on the tenderest new growth: shoot tips, buds, and the undersides of young leaves. They breed extremely fast in mild weather, so a few can become hundreds inside a week. Their feeding curls and distorts soft growth, and the sticky honeydew they excrete coats everything below and turns black with sooty mold. Ants often farm and defend the colonies for that honeydew. A few aphids are normal on almost any plant and a healthy plant shrugs them off; only dense, persistent colonies do real damage, and some aphids also spread plant viruses as they feed.

Watch for: Dense clusters of tiny insects packed onto shoot tips, flower buds, and the undersides of young leaves. Curled, cupped, or distorted new growth that never opens properly. A sticky shine on the leaves - and on whatever sits under the plant - that later goes black with sooty mold. Tiny white cast skins left behind where a colony has been feeding. Ants running steadily up and down the stems, which is often the first thing you notice. Mottled, streaked, or misshapen leaves that do not grow out can mean a virus the aphids brought with them rather than the feeding itself.

Prevent: Go easy on nitrogen: the soft, lush growth that heavy feeding produces is exactly what aphids breed on. Check new growth once a week through spring and early summer so you catch colonies while they are still small, and rub the first few out with your fingers. Leave flowering plants nearby and skip broad-spectrum sprays - ladybugs, lacewings, hoverflies, and parasitic wasps do most of this work for free, and they only stay if there is something for them to eat. Keep ants off the plant where you can, since they protect aphids from those predators. Water steadily so plants are not stressed, and check any new plant over before you bring it home or move it indoors, since aphids usually arrive on something else.

Treat: Knock the colonies off with a hard jet of water and repeat every few days - on most plants that alone ends it. Pinch out or prune off the worst-infested tips rather than treating the whole plant. If colonies keep rebuilding, spray insecticidal soap or horticultural oil directly onto the insects, covering leaf undersides, and repeat weekly until they are gone; treat early or late in the day, and never spray a wilted or heat-stressed plant. Avoid broad-spectrum insecticides - they kill the ladybugs, lacewings, and parasitic wasps that were about to solve the problem for you, and aphid numbers usually come back worse afterward. Anything you spray must be labeled for the plant you are treating; follow that label and observe its pre-harvest interval. On anything you eat, wash leaves, heads, and buds well before use, since aphids hide down in crowns, folds, and tight growth.

Feeding alone rarely damages a blueberry. The reason to keep colonies down is that aphids transmit blueberry scorch and shoestring viruses; remove any virus-infected bush promptly to cut the source.