Mache

Slug damage inside a cold frame is common; lift the frame on mild days, patrol the edges, and keep debris out of it.

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.

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.

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.

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.

It is far more common in mild, wet, maritime winters than in hard-frozen ones.

Pale yellowish patches on the top of the leaves, often bounded by the veins, with a fine grey-violet fuzzy growth on the underside when you turn the leaf over - most visible in morning humidity. Yellowing, limp rosettes in the densest part of the stand, spreading outward. Whole patches collapsing under a closed cover after a run of mild, wet, still weather.

There is no home cure for infected leaves. Pull and remove affected rosettes rather than leaving them to collapse in the stand, open the cover, and harvest the healthy remainder promptly rather than waiting for it to size up. Bin infected material rather than composting it in place. Resow in a different bed with better spacing and better venting - this is a disease you design out rather than spray away.

Airflow is everything. Vent low tunnels, cold frames and row covers on mild days rather than leaving them sealed, sow thinly enough that the stand is not a solid wet mat, and water at the base and in the morning rather than over the leaves in the evening. Rotate the bed - do not follow mache with mache in the same ground season after season - and clear crop debris after harvest. Where mildew is a recurring problem, grow a more tolerant variety such as Vit.

The main disease of corn salad (Peronospora valerianellae), and a cool, damp-weather specialist - which is unfortunate, because cool and damp is exactly when the crop grows. Pale yellow blotches appear on the upper leaf surface with a grey-violet downy growth on the underside, and affected rosettes yellow, collapse and become inedible. It spreads fastest in the still, humid air under a closed cover or in a thickly sown patch, and it survives on crop debris and in the soil between plantings, so repeated mache in the same bed makes it worse.

Vent covers on mild days, pull collapsed rosettes out rather than leaving them, and avoid watering the crop late in the day once cold weather arrives.

Browned, collapsed flowers and buds; soft, water-soaked brown patches on leaves, stems or fruit; and a dusty gray-brown fuzz over the dead tissue. Rot jumping between two pieces of fruit or two petals that touch is the signature, and it often shows up again in the fridge or the storage box days later.

Cut out and destroy infected tissue as soon as it appears, and bag it rather than composting it. Harvest ahead of a prolonged wet spell and store the crop dry and cold. Protective fungicides help through long damp weather, but airflow and sanitation do most of the work.

Space and prune for airflow, water at the base rather than over the top, and go easy on nitrogen, which produces the soft growth it prefers. Clear dead leaves, spent flowers and rotting fruit at every pass, since that debris is where it overwinters. Handle fruit, buds and bulbs gently, because it enters through bruises, and cure and store anything you keep dry and well ventilated.

Botrytis cinerea and its relatives - the fuzzy gray-brown mold of cool, wet, humid weather. It blights flowers and buds, rots ripening fruit, and moves into soft, aging, bruised or frost-damaged tissue through the smallest wound, coating whatever it kills in dusty gray spores. It overwinters on dead plant debris, spreads on air currents and by direct contact between touching tissue, and keeps working after harvest, which is why it also ruins fruit and bulbs in storage.