Sunchoke

Not a pest but the defining problem of growing sunchokes: the crop and the propagule are the same thing. Any tuber, or piece of a tuber, left in the ground sprouts the following spring - and pieces are always left, because the tubers are brittle, scatter well outside the row, and grow deeper than a fork reaches. A stand also creeps outward a foot or two a year on short rhizomes, and shades out whatever is behind its 6-to-10-foot stems. Gardeners commonly report two to four seasons of repeated digging and shoot-pulling to clear a bed they wanted back, and the species has naturalized widely across North America from exactly this persistence. None of this is a reason not to grow sunchokes - it is a reason to decide where they live before you plant one.

Watch for: Shoots emerging outside the bed edge in spring, in paths, in the lawn, or in the next bed over. New shoots coming up through whatever crop replaced the sunchokes, year after year. The stand visibly wider each season than the last. Tubers turning up when you dig anywhere within several feet of an old patch. Shoots appearing around a compost heap or a spot where surplus tubers were dumped.

Prevent: Decide the containment before you plant, because it is far harder to retrofit. Give sunchokes a dedicated permanent bed, a bottomless container or stock tank sunk in the ground, or solid edging buried 18-24 inches around the patch. Never rototill a sunchoke bed or the ground near one - tilling cuts the tubers into hundreds of viable pieces and turns a patch into a field. Walk the boundary every few weeks through the season and pull escaped shoots while they are small and still attached to a findable tuber. Never compost tubers and never dump surplus in a wild corner; bag them for the trash or eat them. Dig the bed over every year, which both improves tuber size and keeps you aware of how far it has traveled.

Treat: Clearing a patch is a season of work, not a weekend. Dig the whole bed over in fall, breaking up every clod and picking out every fragment, then dig it again in spring when the survivors sprout and show you where they are. After that the reliable method is exhaustion: cut or pull every shoot as soon as it reaches six to twelve inches, every time, right through one full growing season - each removal costs the tuber reserves it cannot rebuild without leaves. Sheet mulching with cardboard and a deep mulch layer weakens a patch but rarely finishes it alone. Do not rototill at any stage. Expect stragglers the following year and keep pulling them.

Sunchokes are worth growing - just site them deliberately. The three arrangements that work are a permanent dedicated bed, a sunken bottomless container, or buried edging; the arrangement that fails is a spot in a rotated vegetable garden.

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.

Watch for: 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.

Prevent: 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.

Treat: 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.

Deer and groundhogs both browse sunchoke tops hard through summer, and repeated grazing of a stand cuts tuber size even though the crop itself is underground and untouched. Plants regrow readily, so this is a yield problem rather than a survival one.

A soil-borne fungus (Sclerotinia sclerotiorum) with a very wide host range that rots stems, stalks and crowns in cool, wet, crowded conditions. It grows a distinctive dense white cottony mold on affected tissue and forms hard black resting bodies, the size and look of rat droppings, inside and on the rotted stems. Those resting bodies survive in soil for years, which is why an infected bed stays infected. Infection usually starts where dead flowers, dense foliage or a lodged stem holds moisture against the plant, then spreads downward, and a girdled stem wilts and collapses above the rot.

Watch for: Water-soaked, bleached or tan lesions on stems, often starting at a leaf joint or where a stem fell against damp soil. Dense white cottony growth on the lesion in humid weather. Hard black lumps inside a split stem or on its surface. Whole stems wilting and dying above an otherwise healthy base. Damage worst in the crowded middle of a stand and after a wet spell.

Prevent: Airflow is the whole defense. Space plantings properly, thin dense stands, and keep the ground clear of the previous season's rotted stems. Water at the base rather than overhead and water in the morning. Avoid heavy nitrogen, which makes soft, dense growth that stays wet. Rotate away from other susceptible crops - beans, sunflowers, lettuce, brassicas and carrots are all hosts - rather than following one with another in the same ground.

Treat: There is no cure for an infected stem. Cut affected stems out well below the rot and bag them rather than composting, so the black resting bodies do not go back into your soil. Improve spacing and airflow for the following season and rotate the bed if you can. Fungicides are of little practical use to a home gardener here; sanitation and spacing do the work.

On sunchokes this shows up as stalk rot in a crowded stand late in summer, usually after the tubers are already bulking, so it costs less than it looks like it should. Digging the bed over every year and thinning the stand is the practical control.

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.

Watch for: 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.

Prevent: 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.

Treat: 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.

Colonies build on the soft shoot tips in early summer and are almost always cosmetic here - the crop is underground and the plant has growth to spare. The late-June cut-back removes most of the infested tips along with the height.

Slugs and snails are nocturnal mollusks that rasp ragged holes in soft leaves, shear off seedlings at ground level, and chew into ripe fruit that touches the soil. They feed at night and in the early morning and spend the day hidden under boards, pots, dense mulch, leaf litter, and low foliage, becoming active in exactly the cool, damp, shaded conditions that suit young plants. Damage is heaviest in wet spells and on tender spring growth: a single wet week can erase a row of seedlings while an established, tough-leaved plant of the same species is barely marked. They lay clusters of small pearly eggs in damp soil and under debris, so a garden with plenty of cover carries a resident population year after year rather than being invaded from outside.

Watch for: Irregular ragged holes chewed out of the middle of leaves and along the edges - not the clean-edged cuts a caterpillar leaves. Seedlings that vanish overnight, or that are cut off at soil level with nothing left behind. Silvery dried slime trails across leaves, soil, pots, and paving in the morning: this is the giveaway that tells you it was mollusks rather than an insect. Chewed pits in ripe fruit, especially where it rests on the ground. Damage that shows up on the lowest, dampest leaves first and gets worse after rain or evening watering. Turn over a board, an upturned pot, or a clump of dense mulch during the day and look for the animals themselves sheltering in the cool underneath.

Prevent: Take away the daytime shelter first: lift boards and upturned pots, clear piles of debris, keep dense mulch pulled back from crowns and stems, and give crowded plantings enough airflow to dry out. Water in the morning rather than the evening so the surface is dry by the time they come out. Copper tape around containers and raised beds gives them a shock they will not cross, and it is the one barrier that reliably works. Get plants past the vulnerable stage quickly - start seedlings in pots and set them out at a decent size rather than direct-sowing into a cold wet bed, since most plants stop being worth defending once the leaves toughen. Leave the ground beetles, frogs, toads, and ground-feeding birds alone, because they eat mollusks all night for free and broad-spectrum slug pellets kill them too. Where thick-leaved or resistant varieties exist for what you are growing, they take far less damage.

Treat: Hand-picking works and costs nothing: go out an hour after dark with a headlamp, drop what you find into soapy water, and repeat nightly for a week or two - persistence is what wins, not any single product. Shallow beer traps sunk to soil level catch them too, but need emptying and refilling daily to be worth anything. Iron-phosphate bait is the standard control and is far lower-risk around pets and wildlife than the old metaldehyde products, but it is not harmless: many formulations include EDTA, and a dog that eats a quantity of pellets can develop iron toxicosis. Scatter it thinly per the label, never in piles, and keep dogs off a baited bed. Clear fallen foliage and debris in autumn, where the eggs are laid. In a wet climate this is a population you manage each season rather than one you eradicate - and on most established plants light grazing is cosmetic and needs nothing at all.

Only the first tender shoots in spring are worth defending; once the stems toughen and take off, slugs stop mattering entirely. A wet spring can thin a new planting, so check emerging shoots after rain.

Powdery mildew is a fungal disease that coats leaves - and often stems, buds, and fruit - in a white-to-gray powder that looks like spilled talcum. It is not one fungus but a large family of them, each fairly specialised to its own group of plants, which is why mildew on one crop rarely jumps to an unrelated one beside it. Unlike most leaf diseases it does not need wet leaves: it thrives on warm dry days followed by humid nights, and it takes hold fastest where plants stand crowded in still air or in shade. The coating blocks light, so heavily covered leaves yellow, brown, and drop early. On many plants that is mostly disfiguring and arrives late enough not to matter; where it strips away the leaves a crop still needed to finish, it costs you size, sweetness, and quality.

Watch for: Round white powdery spots on the upper leaf surfaces that spread and merge until whole leaves look dusted. It usually starts on the oldest, lowest, most shaded leaves and works upward, so check there first. Look at the undersides too, and at stems, buds, and flower stalks, which get coated as it advances. Leaves that yellow, brown, curl, or go crisp and drop early under the coating. New growth that opens small, crumpled, or twisted where the fungus has reached the shoot tips. On plants where it gets onto the fruit, a dull gray film, russeted or scarred skin, and cracking. Late in the season, tiny dark specks scattered through the white felt - that is the fungus setting up to overwinter on the debris.

Prevent: Give plants room. Crowding and still air are the biggest single driver, so space at the full recommended distance, thin seedlings properly, and divide or prune out congested growth until air moves through the plant. Full sun and an open position help; deep shade and a still corner against a wall are where it always starts. Water at the base rather than overhead, and water early in the day so nothing stays damp overnight. Keep plants evenly watered - drought stress at the roots leaves them far more susceptible, even though the fungus itself likes dry air. Go easy on nitrogen, since soft lush growth is the most vulnerable. Where resistant varieties exist for what you are growing, choosing one is the single most effective thing you can do on a plant that mildews every year. Clear infected leaves and stems away at the end of the season rather than composting them.

Treat: Start early: sprays protect healthy tissue, they do not clean up leaves that are already coated. Pick off and bin the worst leaves as soon as you see them, and open the plant up by thinning or pruning so air moves through. On anything that regrows quickly, shearing the whole plant back forces a clean flush and beats spraying. If it keeps spreading, potassium bicarbonate, horticultural oil, or neem applied weekly will hold it - cover both leaf surfaces. Sulfur also works, but it burns the foliage of some plants, should never go on in heat, and must not be mixed with or applied close behind an oil spray. Whatever you use must be labeled for the plant you are treating: follow that label and observe its pre-harvest interval on anything you eat. Do not compost badly infected material. Late-season mildew on a plant that is finishing anyway is usually cosmetic; on a crop still filling out it is worth acting on.

Almost universal on the big rough leaves of a crowded sunchoke stand from August on, and almost always cosmetic - the tubers are bulking underground by then and the tops die at frost anyway. Thin the stand and skip the spray.