Growing Small Farms: Seedcorn Maggot

Seedcorn maggots are the larval stage of a fly that infests the seeds and roots of many different vegetable crops. The cool, wet conditions this spring have been ideal for this pest. Seedcorn maggots also prefer feeding in soils with high organic matter.

Control measures: The maggots like moisture, so try not to give more water than the plants need. Crop rotation and sanitation is extremely important and you never want to leave onion culls in the field, because they can harbor larvae that later mature and reinfest fields. Planting as late as possible in the spring allows for rapid seedling establishment (but of course may conflict with market demands). Avoid planting in soils that are high in undecomposed organic matter. If you amend your soil with manure then you want to leave plenty of time for it to decompose before planting. Post-harvest plowing to bury and rapidly decompose crop residues will help to reduce overwintering populations. Row covers placed over transplants at the time of planting can reduce egg-laying activity.

Farmer Doug Jones inspects his onion bed

Farmer Doug Jones of Piedmont Biofarm inspects his onion bed.

dying onion plant in field

It's pretty easy to spot the plants that have been damaged by the maggots. The plant in the middle has wilted and turned yellow.

seedcorn maggot in onion set

Damage to the young onion bulb caused by the seedcorn maggots.

seedcorn maggot in onion set

Close-up of seedcorn maggot feeding on young onion plant. They turn the bulbs to mush.

seedcorn maggot in onion set

More photos of seedcorn maggots in broccoli.

This page last updated February 23, 2011.

North Carolina Cooperative Extension, Chatham County Center
P.O. Box 279, Pittsboro, NC 27312
919-542-8202

Website created and maintained by Debbie Roos, Agricultural Extension Agent.

URL: www.growingsmallfarms.org

North Carolina Cooperative Extension is an educational partnership helping people put research-based
knowledge to work for economic prosperity, environmental stewardship and an improved quality of life.