Peanut

The buried, protein-rich pods are a magnet for foragers, especially as the plants dry down and signal ripeness. Harvesting on time rather than leaving pods in the ground is the most practical defense.

Chewed husks, shells or hulls scattered under the plant, fruit and nuts vanishing as they ripen, and gnawed or half-eaten windfalls. On new plantings: freshly dug holes and scattered soil, bulbs missing or gnawed, dug-up seed rows, vole runways under the mulch, and gaps in spring where you know you planted.

There is no rescue for what has already been eaten, so this is a prevention problem. Re-cover disturbed plantings with mesh promptly, replant losses inside cages, and trap or exclude persistent diggers where that is legal locally. On a large tree, accept that you will share the crop and concentrate on gathering promptly.

For a crop on the plant, timely and frequent harvest is the real defense - gather daily through the ripening window rather than leaving anything to hang, and pick slightly early to finish indoors where the crop allows it. Net or bag what you can reach. For bulbs and sown seed, lay wire mesh or hardware cloth over the planting, plant deeper, use buried wire baskets, and clear away the papery tunics and debris that advertise a fresh planting. Trunk baffles slow climbers on isolated trees, clearing jumping routes from nearby trees and roofs helps, and removing brush cover reduces the rodents sheltering nearby.

Squirrels, chipmunks, voles and mice are the wildlife that competes with you most directly for a crop. They take ripening nuts, seed and fruit off the plant, usually before you judge it ready, and cache what they do not eat. They also dig up freshly planted bulbs and sown seed, and voles tunnel in to gnaw bulbs and roots underground through winter. They climb anything, they know exactly when a crop is ripe, and a determined pair can clear a small tree or a new planting in a few days.

The feeding damage is usually minor, but thrips vector tomato spotted wilt virus in peanut, which can be serious - watch for them on young plants, where early control actually matters.

Silvery-white streaks and fine speckling on leaves and petals, brown discolored patches, distorted buds and blooms that fail to open properly, and tiny sliver-like insects that drop out when you shake foliage or a flower over a sheet of white paper. Worst in hot, dry spells and on drought-stressed plants.

A strong water spray dislodges light infestations, and on a plant that can take it a hard shear and clean regrowth clears them outright. For heavier pressure use insecticidal soap, neem or spinosad, aimed down into the leaf sheaths and buds where thrips actually shelter, and repeat at intervals since eggs and pupae escape a single spray. Spinosad is a registered insecticide: use only a product labeled for the crop you are treating, follow the label exactly, and observe its pre-harvest interval.

Scout early, before the damage reaches the part of the plant you care about. Start with clean planting stock, keep plants well watered since drought-stressed plants suffer worst, avoid heavy nitrogen, clear weedy hosts nearby, and hang blue or yellow sticky traps to catch the first arrivals. Reflective mulch deters them, and predatory mites, lacewings and minute pirate bugs do real work outdoors.

Tiny slender sap-sucking insects that rasp at leaves, buds and petals and drink what runs out, leaving silvery-white streaking and fine flecking, brown scorched patches, and new growth that comes out twisted or fails to open. They breed fast in hot, dry weather, shelter deep in leaf sheaths, folds and unopened buds where sprays struggle to reach, and several species also transmit plant viruses - which is often more damaging than the feeding itself.

Galls form on peanut roots and on the pegs and pods themselves, so pod fill suffers as well as top growth. The same warm sandy soils that suit peanut favor these nematodes, which makes rotation doubly important.

Stunted, yellowing, unthrifty plants that wilt in the heat even though the soil is moist, and poor yields for no obvious reason. Confirm by digging: beady swellings strung along the roots and side rootlets, and root crops that are forked, branched, cracked or knotted rather than clean.

There is no in-season cure. Pull and destroy affected plants rather than composting them, and bring that ground back over several seasons with rotation, resistant varieties and marigold cover crops. Where a crop can be grown in a container of fresh mix, that sidesteps the problem entirely.

Rotate to non-hosts, and grow resistant varieties where they exist for your crop. A French marigold cover crop grown thickly the season before and turned in genuinely lowers populations. Build organic matter and mulch heavily, which feeds the soil life that suppresses them. Plant only clean stock, never move soil from an infested bed around the garden, and solarize badly infested ground through the hottest part of summer.

Microscopic soil roundworms (Meloidogyne species) that invade roots and force them to swell into beady galls. A galled root cannot take up water and nutrients properly, so the plant stunts, yellows, wilts in heat despite watering, and yields poorly, and root and tuber crops come up forked, knobbly, hairy or cracked instead of clean. They are worst in warm, sandy soils and build up steadily wherever a susceptible crop is grown in the same ground year after year. The wounds they leave also open the way for fusarium wilt and rots.

A wide-host-range fungus (it also hits tomatoes, beans, and many vegetables), which is why peanuts shouldn't follow susceptible crops.

Sudden wilting of individual plants, white fungal fans on the lower stem and surrounding soil, and tiny round tan-to-brown sclerotia at the base in hot, humid weather.

Remove and destroy affected plants along with the surrounding soil crust; the sclerotia persist, so rotation and sanitation are the long game.

Rotate with non-host crops (grasses/corn), improve drainage, bury or remove old debris, avoid deep mulch against stems, and don't overcrowd.

A hot-weather soil fungus (Sclerotium rolfsii) that attacks the stem at the soil line, collapsing plants; recognizable by white fan-like fungal growth and tan mustard-seed-sized sclerotia at the base.

Usually shows up late and often travels with leaf spot; together they're the main defoliation threat in humid regions.

Orange, powdery, raised pustules on leaf undersides that rupture and spread; leaves yellowing and dropping when heavy.

Fungicides used for leaf spot also help rust; remove worst-affected foliage and harvest promptly if defoliation sets in. Use only a product labeled for this crop, follow the label exactly, and observe the pre-harvest interval before you dig.

Grow resistant varieties, give good airflow and spacing, rotate, and avoid overhead watering; rust arrives on wind late in the season.

A fungal disease producing orange-brown pustules on the undersides of leaves, often alongside leaf spot, that defoliates plants and reduces pod fill in warm humid weather.