Blueberry

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

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.

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.

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.

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

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.