Gadenin日本語Get the appAphids in the fine foliage
Aphids are the main pest, and the divided leaf hides them well. By the time you notice a sticky feel to the foliage or ants running up the stems, the colony has been there a week and is sitting in the growing point. Chervil is eaten raw and mostly uncooked, so a heavy infestation spoils the crop outright rather than merely slowing it down.
Look under the leaves and into the center of the rosette twice a week while you are cutting. Soft, overfed plants are hit hardest, which is one more reason not to push chervil with nitrogen. A plant growing steadily in shade with no feeding is far less attractive to them.
- Wash them off with water A firm jet of water into the crown from underneath dislodges most of a colony, and aphids knocked off rarely climb back. Repeat every two or three days until you stop finding them.
- Cut out a badly infested plant rather than treating it Chervil is quick from seed and cheap to replace. Pulling one colonised plant out of a row protects the rest and takes less time than any spray program.
- Leave the flowers on a plant you are keeping for seed The flat white umbels feed hoverflies, lacewings and parasitic wasps, whose larvae clear aphids from the whole bed. A single flowering chervil is worth keeping for this alone.
Wash cut chervil in a bowl of cold water rather than under a tap and lift the leaf out rather than pouring it off. Aphids and grit sink, and the fragile leaf is not battered.
Slugs and snails on young plants
Chervil seedlings are soft, low growing and sown at exactly the seasons when slugs are busiest. A whole row can vanish overnight in damp autumn weather, and because emergence is slow anyway, gardeners often assume the seed failed rather than that something ate it.
Check after dark with a torch when a row disappears. If you find slugs, protect the next sowing rather than mourning the last one. The risk drops sharply once the plants have four or five true leaves, so the vulnerable period is only two or three weeks long.
| Symptom | Cause | Response |
|---|---|---|
| Seedlings gone, no stumps, slime trails | Slugs or snails | Check after dark, trap or barrier the row |
| Seedlings collapsed at soil level, stems pinched | Damping off or cutworm | Improve airflow, sow thinner, dig around the stems |
| Row never emerged at all | Old seed or a dried out surface | Test the seed, keep the drill damp next time |
| Leaves shredded, ragged edges only | Caterpillars or earwigs | Pick off by hand in the evening |
Never mulch a row until the seedlings are thinned and standing. Mulch laid over a young row gives slugs cover and moisture right where the softest growth is.
Leaf miner tunnels
Chervil belongs to the same family as carrots, parsley and celery, and it can pick up the leaf miners that go for those crops. The sign is a pale winding tunnel or a translucent blotch inside the leaf, with the grub visible against the light. The damage is cosmetic on a large plant but ruins a leaf you were going to serve whole.
Picking is the whole treatment. Squash the grub inside the leaf between finger and thumb, or take the affected leaves off and bin them rather than composting them. Sprays do not reach a larva sitting between the two leaf surfaces, so there is nothing else worth trying at garden scale.
- Pick affected leaves off twice a week Removing the leaves removes the next generation. A weekly walk down the row with a bucket keeps the problem to a handful of leaves rather than half the crop.
- Cover a badly affected row with fine mesh Insect mesh over hoops from the day you sow keeps the adult flies off. It also suits chervil in other ways, since it casts light shade and holds the soil cool.
- Keep chervil away from last year's carrot bed Rotating it around the garden with the rest of the carrot family breaks the cycle of anything that overwintered in the soil there.
Crown rot and mildew in damp weather
The autumn sown crop sits through the wettest part of the year, and the main threat to it is not cold but standing water. Chervil is hardy well below freezing, yet a plant in a puddle rots at the crown in a mild damp winter. The first sign is a soft brown base with foliage that pulls away in your hand.
Powdery mildew shows up at the other end, on crowded spring plants in dry weather, as a gray white bloom on the older leaves. Neither problem is worth treating chemically. Both come back to the same two things: spacing and drainage. A row thinned properly and grown on soil that drains gets away with almost anything.
| Problem | What you see | What to do |
|---|---|---|
| Crown rot | Soft brown base, foliage lifts away | Pull the plant. Improve drainage or raise the bed |
| Powdery mildew | Gray white bloom on older leaves | Cut out affected leaves, thin the row, water at the root |
| Damping off | Seedlings toppling at soil level | Sow thinner, ventilate, avoid watering in the evening |
| Leaf spot | Small dark spots that spread in wet spells | Remove affected leaves, keep the foliage dry |
| Winter mud splash | Grit ingrained in the leaf, gritty when eaten | Mulch between plants or grow the winter crop under cover |
Note the date you first see aphids, mildew or missing seedlings each year. Those first dates repeat closely from season to season, and knowing them means you can cover or check a row a week before the trouble arrives rather than a week after.