Gadenin日本語Get the appAutumn: flea beetles and caterpillars on young plants
Late-summer sowings emerge into the warmest, buggiest part of the year, and the seedling stage is the only time this crop is genuinely fragile. Flea beetles pepper the cotyledons with tiny round holes and can kill a seedling outright in a hot, dry week. Fine insect mesh laid over the bed from the day of sowing is the whole answer, and it costs nothing to leave on until the plants have six true leaves.
Caterpillars from white and cabbage moths are the other autumn problem, and they are worse here than on a leafy brassica because a caterpillar in the crown chews the growing point. Lose that and the plant never makes a main shoot. Check the undersides of leaves twice a week while the weather is warm and squash the egg clusters, which are laid in neat groups and are far easier to deal with than the caterpillars they become.
Both problems stop mattering once the nights cool. If your plants get through to a stocky ten-leaf rosette with an intact center, they are effectively out of danger until spring.
| Pest | Season | First sign | Response |
|---|---|---|---|
| Flea beetles | Late summer | Shot holes in seedling leaves | Mesh from sowing; keep soil damp |
| Caterpillars | Late summer to autumn | Egg clusters under leaves | Squash eggs twice weekly; mesh |
| Slugs | Autumn and mild winter | Ragged holes, slime on crown | Clear leaf litter; check after dark |
| Pigeons | Hard winter | Leaves stripped to the ribs | Net at a height they cannot press onto |
| Aphids | Late winter to spring | Gray colonies in bud clusters | Cut and remove affected shoots |
| Downy mildew | Cold wet spells | Yellow blotches, gray felt beneath | Ventilate covers; strip lower leaves |
Winter: slugs at the crown and birds overhead
Slugs do not stop in a mild winter, and they shelter in exactly the place that hurts: the layer of collapsed outer leaves against the crown. Stripping those leaves off every few weeks removes the shelter and lets you see the damage. Look for slime trails on the stem and clean-edged holes in the innermost leaves, and go out with a torch on a mild damp evening to confirm.
Pigeons are the other winter problem, and they are opportunistic: they will ignore a bed for two months and then strip it in a single hard-weather week when other food is gone. Damage is unmistakable, with leaves reduced to bare midribs. Netting works only if it is held clear of the foliage on hoops, because birds will simply stand on a net laid directly over plants and eat through it.
Neither of these is fatal by itself. A plant can lose most of its outer leaves to birds and still make a decent main shoot, provided the crown is untouched. Assess the center of the plant before deciding whether something is worth replacing.
Spring: aphids in the bud clusters
This is the pest that actually costs you the crop. Mealy gray aphids overwinter in sheltered crowns and multiply fast as soon as it warms, and they head straight for the newest, softest growth, which here is the bud cluster you were about to eat. A colonised shoot is unusable, because you cannot wash the aphids out of a tight bud cluster.
Catch it early by turning back the newest leaves and looking into the center of each plant on your regular harvest walk. At the first sign, cut the affected shoot off entirely and take it away from the bed rather than dropping it between the plants. If a whole plant is infested through the crown, pull it. One heavily colonised plant will reseed the entire row within a fortnight.
Distorted, puckered leaves and sticky patches are secondary signs, but by then the colony is established. The reason to check every two or three days during harvest is as much about aphids as it is about buds.
Never leave a finished plant standing in flower next to a bed you are still cutting. Flowering plants attract and sustain aphid colonies, and the crop is precisely the part they colonise. Pull spent plants promptly.
Soil-borne trouble and knowing when to give up
A plant that wilts on warm days and recovers overnight, and does not respond to watering, has a root problem. Lift one and look. Swollen, distorted roots mean clubroot, which lives in the soil for many years and means no brassica of any kind should go in that ground for a long rotation. Brown, soft, foul-smelling roots are rot from waterlogging, which is a drainage problem you can fix.
Because this crop occupies the ground for six months or more, rotation discipline matters more than for a fast salad crop. Keep a three or four year gap between brassicas on the same ground, and count this crop as a brassica for that purpose even though you are eating the flowers.
Give up on a plant when the growing point is gone, when the crown is soft, or when a spring aphid colony has reached the center. In each of those cases the plant will never produce a usable shoot and it is occupying space and harboring problems. Pulling it early is the productive decision.
Log where trouble appears, not just that it appeared
Note the date you first see each problem and, crucially, which part of the bed it started in. Aphid outbreaks, slug damage and winter rot all begin in the same places year after year, usually the sheltered end, the low corner or the row against a fence. Two seasons of records turn that into a map, and the map tells you where to put the mesh, where to raise the bed and which end to check first.
Recording the date of the first aphid sighting is the most valuable single entry, because it is usually within a few days of the same point each spring and it tells you when to start looking rather than reacting.