How to Manage Pests
UC Pest Management Guidelines
Scientific Name: Delia platura
In this Guideline:
The seedcorn maggot is the larva of a small, light gray
fly that is about 0.15 inch (4 mm)
long. The whitish, legless maggots are about 0.3 inch (8 mm) long and attack
the planted seed of a number of crops during the winter and early spring
months, particularly if there is a cold period that prevents quick germination
of the seed. Maggots may overwinter in the soil or hatch from eggs laid in
The maggot attacks germinating
seeds or transplants, but is only a
pest early in the season before the soil warms up. Little damage is likely to
occur once favorable growing conditions set in. Seedcorn maggots are
particularly damaging when residues of the previous crop have not thoroughly
decayed before planting cucurbits.
A preventive seed treatment is particularly important when planting
in no-till, conservation-till, and when planting through cover crops to prevent
seed corn maggot damage. Additionally, good field sanitation, and production
measures that ensure rapid seed germination are important in controlling seed corn maggots.
Fields with moist, heavy-textured soil usually have the worst
problem with this pest. To reduce attractiveness of the field to egg-laying
adults, disc or plow early in the season to incorporate residues from the
previous crop and allow time for residues to completely decompose before
planting. Destroy weed growth. Avoid planting cucurbits after root crops or
cole crops, including cabbage, cauliflower, broccoli, and Brussels sprouts, and
after fall tomatoes. Assure rapid seed germination by planting in moist soil
and not too deep (1.25 to 1.5 inch depth is ideal for melons) when weather
conditions are ideal. The longer the germination the greater
the risk of infestation. Late-season planting may avoid the early season
infestation of this pest.
Organically Acceptable Methods
Cultural controls are acceptable to use in an organically certified
Monitoring and Treatment Decisions
A preventive seed treatment is the best method of control.
|When choosing a pesticide,
consider information relating to water quality and impact on natural enemies and honey bees. Not all registered pesticides are listed. Always read the label of the
product being used.
CAUTION: Do not use treated seed for human
consumption, for livestock or poultry, or for oil purposes. Label treated seed as follows: TREATED SEED. DO NOT USE FOR FOOD, FEED, OR OIL.
||MODE OF ACTION GROUP NUMBER1: 1B
||COMMENTS: For use in
melon fields only; broadcast just before planting and incorporate. Avid drift and tail water runoff into surface waters.
||COMMENTS: Wait at least
14 days after fumigation before planting. Fumigants such as metam sodium are
a source of volatile organic compounds (VOCs) but are minimally reactive with
other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
C. S. Stoddard, UC Cooperative Extension, Merced & Madera counties
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
L. D. Godfrey, Entomology, UC Davis
C. B. Fouche, UC Cooperative Extension, San Joaquin County
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties
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