Lowbush Blueberry

0 to 5.2, lower than highbush - and it is the number-one reason home patches fail. Test before planting, correct with elemental sulfur a season ahead, and keep pine bark or sawdust mulch topped up.

Yellow leaves with a distinct network of green veins, worst on the NEWEST growth at the shoot tips - that vein pattern is what separates it from a nitrogen shortage, which yellows the oldest leaves uniformly. Whole plants going progressively paler over a season rather than suddenly. Brown scorched leaf margins and shoot-tip dieback in advanced cases. Symptoms concentrated on the side of a plant nearest a foundation, wall, path, driveway, or a stretch of limed lawn. One plant affected while a neighbor that does not need acid soil looks perfect.

Correct the soil, and use iron only to buy time. Chelated iron sprayed on the leaves or drenched into the root zone greens a plant up within a week or two, but it wears off in a season and has to be repeated indefinitely - it fixes nothing. The real fix is lowering pH with elemental sulfur applied to the surface and watered in, retesting each season until you are in range, then holding it there with acidic mulch and acid fertilizer. Expect one to two years; there is no fast route. Note that other shortages look identical - manganese deficiency produces the same yellow-with-green-veins pattern on some plants - so a plant that does not green up from iron should be tested rather than dosed again. Where the pH is high because of nearby concrete or genuinely calcareous subsoil, the plant is in the wrong place, and moving it into a properly built acidic bed or container will succeed where years of amendment will not.

Test the soil pH before you plant, not after, and match the plant to the ground - an acid-loving plant in limy soil will never be truly healthy however it is fed. Where the pH is too high, acidify with elemental sulfur worked in the season BEFORE planting, since sulfur takes months of soil biology to work and cannot be rushed, and retest before you commit plants. On genuinely alkaline ground the honest answer is often a raised bed of acidic mix, or a container, rather than fighting the native soil forever. Keep an acidic organic mulch topped up - pine bark, pine straw, sawdust - and site acid-lovers away from concrete foundations and mortared walls, which leach lime for decades. Never apply lime, wood ash or mushroom compost where the roots reach, use acid-forming fertilizers such as ammonium sulfate, and improve drainage, because cold waterlogged soil hurts uptake even at the right pH.

Not an infection but a nutrient lockout caused by soil chemistry. Iron is abundant in almost every soil, but as pH rises it converts to forms roots cannot take up, so a plant that needs acid ground slowly starves for iron while standing in soil full of it. The symptom is unmistakable: new leaves go pale yellow or cream while the veins stay green, giving a fine green net over a yellow leaf. It shows first and worst on the newest growth, because iron does not move around inside a plant to be recycled. It does not spread between plants, does not respond to fungicides, and does not resolve on its own - left uncorrected the plant grows less each year, leaves get smaller and paler, shoot tips die back, crops fall away, and it eventually dies. Worst near concrete, mortar, paths and limed ground, and in cold, wet, compacted soil.

Rake carefully after each pick, and get harvested fruit cold quickly - larvae in just-picked berries stop developing at refrigerator temperature.

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.

At home, re-mulch under the crop-year half each late winter to bury the mummies before the spring spore stage.

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.

Because only half the patch fruits each year you only ever have to net half of it. Chipmunks and mice work the mat from below and netting does nothing about them.

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.