Walnut

Young trees are far more at risk than mature ones; the juglone-rich foliage deters deer somewhat but not reliably, and antler rubbing on young trunks is the bigger danger.

Growth cleanly missing overnight, with the plant browsed back to a level line about as high as a deer can comfortably reach. Ragged, torn stem ends rather than the clean angled cut a rabbit leaves - the single most reliable identifier. Buds and flowers gone while the foliage below is untouched, since deer often take the best part first. Hoof prints and droppings in soft ground near the damage. Repeat visits, with fresh damage each morning once a planting has been found. On young trees, shredded and stripped bark and broken low branches in autumn - that is antler rubbing rather than feeding.

There is no chemical fix, only exclusion and recovery. Get physical protection up immediately after the first damage, because deer return to a known meal, and reinforce or rotate whatever you were relying on before. Most plants regrow from browsing if the crown and roots are intact - feed and water a grazed plant and protect the regrowth while it comes back. What does not recover in the same season is anything whose buds or flowers have been taken, and a young tree whose bark has been rubbed right around the trunk is usually lost. Where deer pressure is genuinely heavy, the honest answer is to fence properly or to grow the plants deer leave alone, rather than to keep replacing losses.

Fencing is the only thing that reliably works. Eight feet is the standard for excluding deer, or two parallel four-foot fences a few feet apart, which they will not jump because they cannot judge the landing. Short of that, cage individual plants: a sturdy wire cage or trunk guard around every young tree, left on until the trunk is thick and the canopy is above browse height, prevents both browsing and antler rubbing and is the single highest-value thing you can do for a young tree. Repellent sprays do help at moderate pressure, but they wash off and deer habituate, so reapply after rain and rotate between different types through the season. Motion-activated sprinklers, scent deterrents, and noise devices work for a while and then stop. Siting matters too: plants close to the house, in daily traffic, and screened behind other planting get browsed less than the same plant out at the boundary.

Deer are the largest garden problem across much of the country, and where pressure is high they set the limit on what you can grow at all. They browse at night and around dawn and dusk, taking tender shoots, leaves, buds, flowers, and fruit within about five feet of the ground, and they come back night after night to anything they have found and liked. Because they have no upper incisors they tear rather than cut, leaving ragged stem ends - that is how you tell deer damage from a rabbit's clean angled cut. In fall, bucks rub their antlers on young trunks and can strip the bark right around a stem, which kills a young tree outright. Palatability varies enormously between plants and between seasons: a herd short of food in late winter eats things it ignores in June, and no plant is truly deer-proof.

The kernel usually stays sound - the harm is messy, stuck-on husks and stained shells, plus darkened kernels if hulling is delayed.

Black, soft, slimy husks in late summer that cling to the shell, small white maggots inside the rotting husk, and stained, hard-to-hull nuts.

Rarely warrants spraying on a home tree - sanitation (removing dropped, infested hulls) is the main control, and the kernel inside stays sound. Just hull affected nuts promptly and clean the stained shells.

Gather and destroy dropped, infested nuts promptly to break the cycle; hang yellow sticky traps to monitor emergence; hull nuts immediately after gathering so the maggots can't taint the kernel.

The signature late-season walnut pest: a fly that lays eggs in the husk, and whose maggots tunnel through it, causing the husk to blacken, soften, and rot, and to stick tightly to the shell so it won't hull cleanly - staining the shell and darkening the kernel if left on, though the maggots rarely reach the nut itself.

On walnuts the larvae enter through the husk and feed on the kernel, so it shows as early nut drop and tunneled kernels rather than a wormy fruit. Usually two generations a season here; the first, in early summer, is the key one to disrupt. Bt is not a control - the newly hatched larva is inside the nut within hours - and on a large home tree sanitation matters most.

Small entry holes ringed with brown frass, early fruit or nut drop, and a tunnel running to the seed cavity or kernel when you cut or crack a damaged one open.

Spinosad timed to egg hatch (the traps tell you when), or codling moth granulosis virus (CpGV) as a targeted biological. Bt does not work on codling moth - the newly hatched larva bores straight into the fruit within hours and never eats enough surface tissue to take in a dose. Use only a product labeled for the crop you are treating, follow the label exactly, and observe the pre-harvest interval before you pick. Sanitation and fruit-bagging matter more than any single spray.

Hang pheromone traps to time any spray; gather and destroy dropped fruit and nuts promptly to break the cycle; bag individual fruits or apply kaolin clay for spray-free control.

The classic 'worm in the fruit': larvae of a small gray moth tunnel in from the skin and feed at the core or kernel, packing the entry hole with sawdust-like frass and ruining the crop for keeping. The same moth works apples, pears and walnuts.