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Seedcorn Maggot

Seedcorn Maggot

Delia platura

insect

In a Nutshell

    Maggots feed on sprouting seedlings and seeds, damaging the growing tissuesClear damage from the maggots’ feeding is visible on young leavesSeedlings develop into whithered, stunted, deformed plants with low yieldsWet soils and prolonged periods of cool weather and high humidities favor the pest

Hosts: %1$s

· Bean · Pea · Cabbage · Lettuce · Spinach · Onion · Garlic · Leek · Maize

Symptoms

Maggots feed on organic matter in the soil and on sprouting seedlings. They also burrow into the seeds, often destroying the growing tissues and preventing germination. If they develop at all, there is clear damage from the maggots’ feeding visible on the young leaves. Rot of tissues can ensue. Seedlings may develop into whithered, stunted, deformed plants which give few seeds with low quality and consequently low yields. If soils are wet and if there are prolonged periods of cool weather and high humidities, the damage can be important.

Trigger

The adults resemble house flies in color, but they are smaller and more slender. They overwinter in soil close to old roots and plant debris. Adults emerge in spring as early as seeds are being planted. Females lay their eggs in moist soils that contain large quantities of decaying material or manure. Yellowish-white, legless larvae hatch after about a week and then start to eat on decaying organic matter and on seedlings. Damage is greater in cool, wet weather conditions which favor the life cycle of the pest and its feeding activity. Warm and sunny weather in turn hinders the deposition of eggs and also makes plants grow faster and hardier.

Biological Control

Due to its underground life, seedcorn maggots do not appear to have a great number of natural enemies. However, predation by ground beetles, spiders and birds on adults does occur. The larvae can be affected by fungus diseases. However, predators as well as fungal diseases do not provide sufficient control. The flies are naturally attracted to bright colors, so they can be trapped in bright buckets with soapy water.

Chemical Control

Always consider an integrated approach with preventive measures along with biological treatmetns if available. Seeds can be treated with an insecticide to ward off the maggot. Pesticides like thiamethoxam or clothianidin can be used. Soil-applied insecticides can also be used.

Preventive Measures

    Plant in dry soils with little organic contentEnsure shallow planting during warm and sunny weatherIf applying manure, wait some weeks before plantingUse cover crops such as grassesHandle the seeds with care so that you don't injure themDestroy weeds in and around the fieldsA fine mesh net on your seedbed keeps the maggot flies awayPlow and bury plant debris deep into the soil