Cutworms are the larvae of several night-flying moth species (Order Lepidoptera, family Noctuidae). Cutworms are a common pest of a wide range of vegetable crops, including carrots, celery, lettuce, onion, tomato, pepper, eggplant, cole crops, rutabaga, beans, cucurbit crops, sweet corn, and others. Most cutworm species are solitary feeders found in the soil; however, some species occasionally attack the foliage and fruit of some vegetable crops.
Management of Cutworm in Radish
The Life Cycle of Cutworm
- The life cycle of cutworms in eggplant is similar to that of other plants. The female adult moth lays eggs on the underside of the leaves or stems of the eggplant plant. After a week, the eggs hatch into small larvae that begin to feed on the eggplant.
- The larvae will moult several times, growing larger with each moult. They will continue to feed on the eggplant until they are fully grown, which usually takes a few weeks.
- When the cutworms are fully grown, they burrow underground to prepare for the pupal stage. They will build a small pupal chamber in their borrowed space and begin developing into adult moths.
- Cutworms pupate for several weeks before emerging as fully formed adult moths. Once they have emerged from the pupae, they will mate and lay eggs, starting the cycle anew.
Factors Favoring Population Increase in Cutworm in the Field
- Mild winter temperatures and early spring warming
- Wet weather in the spring, which promotes plant growth and cutworm feeding
- The abundance of suitable host plants for feeding and egg laying
- Lack of natural enemies such as predators, parasitic wasps, and tachinid flies
- Reduced tillage practices leave more plant debris on the soil surface for cutworm larvae to hide in
- Over-fertilization of fields, which can increase plant growth and attract cutworms
Identification of Cutworm in Radish Field
- Cutworms have a smooth appearance with few hairs and curl into a tight ‘C’ shape when disturbed.
- Cutworms of various species can have distinct physical characteristics and colorations ranging from brown or tan to pink, green or grey, and black.
- Cutworms can be uniformly colored, spotted, or striped.
- Some cutworm larvae appear dull, while others appear glossy.
Damage Symptoms of Cutworm in Radish Field
- Clipped seedlings or leaves: Cutworms feed on seedlings and young plants by clipping them off at or below ground level. They also chew leaves that touch the ground, causing them to wilt or die.
- Multiple plants affected: Several plants in a row will often be wilted or clipped as cutworms feed on plants close together.
- Recurring damage: Cutworm damage often occurs in the same fields and parts of fields year after year.
- Damage at night: Cutworms feed mostly at night, and during the day, they are usually found just below the soil surface or under dirt clods.
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