Pecan

The reason the harvest and storage advice on this page keeps saying to cull holed nuts - a few weevil grubs will infest a whole stored batch.

Nuts dropping early in August and September; a clean, perfectly round hole about 1/8 inch across in the shell; a white, legless, brown-headed grub inside an otherwise sound-looking nut; long-snouted brown weevils jarred out of the canopy onto a sheet.

There's no home rescue for an infested nut. Cull every holed or suspiciously light nut before storing, and destroy them (burn, bag, or deep-bury) rather than composting under the tree. Orchards time trunk and canopy sprays to adult emergence; on a 70-foot backyard tree, sanitation is the realistic control.

Gather dropped nuts promptly and often through the whole drop window so grubs can't leave the nut and burrow into the soil - that one habit breaks the cycle better than anything else. Keep chickens or livestock under the tree if you have them, and don't leave culled nuts lying beneath the canopy.

The most damaging pecan nut pest across much of the native range: adult weevils emerge from the soil in late summer, and the females drill through the shuck of hardening nuts to lay eggs inside. The grubs eat the kernel from within, so a nut that looks and weighs almost right can be hollow, and when the grub chews its way out it leaves a clean round hole in the shell.

Distinguish from a normal 'June drop' - casebearer damage shows the entry hole and frass; June drop nutlets are clean.

Small nutlets in late spring with a tiny entry hole at the base and dark frass (sawdust-like droppings) webbed around it; whole clusters of nutlets shriveling and dropping a few weeks after bloom; nutlets webbed together.

Timing is everything and it is narrow: sprays only work in the few days between egg-laying and the larva boring in, which is why orchards follow regional casebearer forecasts. A backyard tree usually rides out the loss, since pecans set far more nutlets than they can fill.

Nothing you plant your way out of - scout the nutlet clusters weekly from just after bloom, and let the parasitic wasps, spiders, and lacewings that normally keep casebearer in check do their work by not spraying broadly for aphids.

A small gray-brown moth whose larvae attack pecans right after nut set. Each larva bores into a tiny nutlet at the base of the cluster and tunnels on from nut to nut, so one caterpillar can destroy several nutlets in a cluster - the main cause of early nutlet loss in the South.

Pecans have two: the yellow pecan aphid, which mainly leaves honeydew and sooty mold on the lower leaves, and the black pecan aphid, which is more damaging and causes yellow leaf blotches and early defoliation. Beneficial insects usually handle both on a large home tree; heavy late-season black-aphid outbreaks are an orchard problem more than a garden one.

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.

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.

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.

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.