Cutworms
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Treat, then re-check in 5–7 days
Pick off the worst material, apply the organic option below, and look again after five to seven days. If the spread continued, escalate rather than repeating the same treatment.
Carried by insects
An insect moves it plant to plant, so controlling the carrier matters as much as treating the symptom. Check for the vector before assuming the plants infected each other directly.
Safe to compost
No pathogen carries over on this material, so it can go on an ordinary heap with the rest of the garden waste.
When and where to look
Scout the planting while temperatures hold between 12°C and 30°C, in dry air below 60%.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Cutworms are the soil-dwelling caterpillars of several noctuid moths. They feed at night, severing young plants at ground level, and hide just below the surface by day — which is why a gardener finds toppled seedlings each morning and no culprit anywhere.
Symptoms
Young plants cut clean through at soil level and left lying beside the stump. Later in the season, surface grazing on potato tubers and carrot shoulders. Scrape the soil within a few centimetres of a felled plant and a fat grey-brown caterpillar curls up in a C shape.
Organic Treatment
Search the soil around each fresh casualty in the morning — the culprit is almost always within 5 cm. Push a collar of cardboard or a cut plastic bottle into the soil around each transplant. Water the bed heavily: cutworms thrive in dry soil and parasitic nematodes applied to moist warm soil work well.
Chemical Treatment
Garden insecticides give poor results because the caterpillars are underground by daylight. A late-evening application of an approved contact spray to the soil surface is the only timing with any chance of contact.
Prevention
Keep the plot weed-free from midsummer — the moths lay on weeds and grassy edges. Hoe regularly to expose caterpillars to birds, and rotate so an infested bed carries a less vulnerable crop next season.
Crops at risk
Related problems
Cutworms risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.