Flax

Flax rust is famous in plant science (the 'gene-for-gene' resistance model came from it); resistant varieties largely control it in home gardens.

Orange, rusty, raised pustules on leaves and stems that later turn dark, with yellowing and weakened, spotted stems.

Little to be done once heavy; resistant varieties and rotation prevent it, and it especially matters for fiber flax where it mars the stems.

Grow resistant varieties (the primary defense - flax rust resistance is a classic case in plant pathology), rotate, give airflow, and remove crop debris.

A fungal disease (Melampsora lini) producing orange-to-brown pustules on flax leaves and stems, sapping the plant and, importantly, damaging fiber quality in fiber flax; historically a serious flax disease.

The reason flax shouldn't be grown on the same ground year after year ('flax sick soil') - rotation and resistant varieties are essential.

Wilting, yellowing, and browning of plants (often in patches), stunting, and death, worse where flax has grown before ('flax sick' ground).

No cure for infected plants - remove them, and rotate away from flax for several years; resistant varieties and rotation are the real controls.

Grow resistant varieties; rotate away from okra (and related mallows) for several years; ensure good drainage; control root-knot nematodes, which open the door to wilt.

A soil-borne fungus (Fusarium oxysporum f. lini) that infects flax roots and clogs the water-conducting tissue, causing wilting, yellowing, stunting, and death, and persisting in the soil for years - the classic 'flax sick' soil problem.

Only a concern for a seed harvest: birds work the ripening bolls and seed vanishes from any that have split. Net small seed plots as the bolls ripen and pull the crop before they fully split and shatter. Fiber flax is pulled at yellow-ripe before seed forms, so birds are not an issue for it.

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.