Gadenin日本語Get the appTell the cause from the symptom
Long white radishes get the same pests as round ones, but because the root runs deep, shape problems in the root stand out more. Sort leaf symptoms under insects and root symptoms under soil, water and timing, and the cause is usually obvious. With only a month to harvest, netting and soil preparation beat spraying.
| Symptom | Cause | Response |
|---|---|---|
| Many tiny 1 to 2 mm holes in the leaves | Flea beetles | Insect netting from the day you sow |
| Large bites from the leaf edge, black droppings | Cabbage worms, cutworms | Hand-pick; netting |
| Clusters of tiny insects, curled leaves | Aphids | Hose off; widen spacing |
| Windowpane patches eaten from the underside | Diamondback moth larvae | Netting; clear nearby brassica debris |
| Bent or forked root | Stones, hardpan, raw compost | Dig 6 to 8 in deep and remove stones |
| Lengthwise split, hollow center | Wet-dry swings, late harvest | Steady water; pull when shoulders show |
| Wilting at midday, galls on the fine roots | Clubroot | Lime the soil; rotate away from brassicas |
| Soft, foul-smelling rot at the crown | Bacterial soft rot | Drainage, avoid wounds, pull early |
Flea beetles: net them out
Dozens of pinholes 1 to 2 mm across are the work of flea beetles, shiny black beetles about 0.1 in (2 to 3 mm) long that jump like fleas when touched. If they strip the seed leaves the seedling stalls, and their larvae in the soil graze the root surface, leaving dark tracks on the white skin. They are active from spring into fall and are still plentiful during an early-fall sowing.
- Net on the day you sow Adults fly in, and by the time sprouts show it can be too late. Lay insect netting with mesh under 1 mm directly on the bed the day you sow and bury the edges so there are no gaps.
- Keep it on until harvest Lift it only to thin or feed, and put it back as soon as you finish. If anything got in, pick it out while the net is up.
- Clear nearby brassica leftovers Old kale and cabbage stumps and weeds like shepherd's purse are breeding sites. Clean up around the bed before sowing to cut the numbers.
- Holed leaves are still edible Light damage does not hurt growth and the greens are fine once washed. Only pull seedlings that were badly chewed at the seed-leaf stage and resow.
Cabbage worms and cutworms: find and remove
Big bites from the leaf edge with black pellets below mean cabbage worms or cutworms. Cabbage worms are green caterpillars on the undersides of leaves by day; cutworms feed at night and hide in the soil at the base of the plant. Netting keeps them out, but a cabbage white butterfly can slip under a loose edge.
- Check under leaves and at the base Find droppings, then look at the underside of the leaf directly above. If nothing is there, scratch the soil at the crown and you will find a curled cutworm. Pick it off with chopsticks.
- Remove egg masses with the leaf Cutworm moths lay hundreds of eggs in a cluster under a leaf. Cut the whole leaf off and dispose of it.
- Spray only as a last resort With a month to harvest and edible greens, use only products whose preharvest interval you can meet. For a handful of worms, fingers are more reliable.
Aphids and diamondback moth
Tiny insects clustered on new growth with curling leaves are aphids; windowpane patches eaten from below are diamondback moth larvae. Both build up on crowded plants with poor airflow and on soft, overfed foliage. Thinning on time and feeding lightly is the best prevention.
- Hose them off A few aphids come off with a firm spray of water on the undersides of the leaves. Since you eat the greens, tape works too.
- Pull crowded plants for airflow Wherever spacing is under 1.2 in (3 cm), pull the extras to let air through. They go in the kitchen as thinnings.
- The one that dangles on a thread A small green caterpillar that drops on a silk thread when touched is the diamondback moth. Sprays work poorly on it, so hand-pick and rely on netting to keep it out.
Bent and split roots: soil and water
A root that comes up bent or forked ran into a stone, a hard layer or a lump of raw compost. It is not a disease; dig 6 to 8 in (15 to 20 cm) and remove the stones next time and it goes away. Lengthwise splits come from a soaking after a dry spell, hollow centers from leaving the roots too long, and both are fixed by steady watering and timely harvest.
| Root symptom | When it happened | Prevention next time |
|---|---|---|
| Bent tip, forked | Soil prep before sowing | Dig 6 to 8 in deep; remove stones and lumps |
| Dark tracks on the skin | During growth (flea beetle larvae) | Netting to stop adults laying eggs |
| Lengthwise split | Sudden water before harvest | Never bone dry; light watering before rain |
| Hollow center | Harvested late | Test-pull when shoulders show; clear within two weeks |
| Green, tough shoulder | Shoulder exposed to sun | Hill soil over the crown |
Beds along a foundation often hold construction gravel. The first year, dig 8 in (20 cm) with a spade and see what turns up before you sow.
Clubroot and soft rot
Plants that wilt at midday and recover by morning, with galls on the fine roots when pulled, have clubroot, a soil disease of acidic, poorly drained ground that has grown brassicas repeatedly. A crown that goes soft, watery and foul-smelling is bacterial soft rot, which enters through cracks in overgrown roots and insect wounds. Neither can be cured; pull affected plants and prevent through soil and timing.
- Rotate away from brassicas Do not follow kale, cabbage or daikon with radishes; grow something else for a crop or two. In a tiny bed, replace the soil or move to a planter.
- Lime to raise the pH Two weeks before sowing, work in garden lime at about 3 oz per square yard (100 g per square meter). Clubroot thrives in acidic soil.
- Avoid wounds and late harvest Soft rot enters through damage. Do not nick neighbors while thinning or pulling, and harvest as soon as shoulders show. Pull and discard any rotting plant at once.