How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The seedcorn maggot adult is a slender, light gray fly, about 0.2 inch long; it is less robust appearing than the housefly. The whitish eggs are slightly curved with their posterior bluntly rounded. Mature larvae range from 0.2 to 0.25 inch in length, are white to whitish yellow, cylindrical, and taper anteriorly. Pupae are small brown capsules. In California, the seedcorn maggot is abundant primarily in spring, during or following a wet cycle, and is most common in fields containing a high amount of residue from a previous crop or where manure has been spread.

DAMAGE

Seedcorn maggots burrow into corn seeds and prevent germination. Slow emergence and poor stand establishment are signs of seedcorn maggot activity. Where slow, spotty emer­gence is observed, dig up seeds and inspect for maggot feeding. Soil and weather conditions such as cool soil temperature and periods of excessive moisture favoring slow seed germi­nation and seedling emergence increase susceptibility to seedcorn maggot infestation.

MANAGEMENT

A preventive treatment (seed or broadcast) is the best method of control. To reduce attractiveness of a field to egg-laying adults, disc or plow early in the season, incorporating residues from a previous crop and destroying weed growth. Plant under ideal soil and weather conditions to assure rapid seed germination and minimize the seedcorn maggot problem.

Organically Acceptable Methods
Discing to incorporate crop residues and destroy weed growth and planting under ideal conditions are the best way to manage this pest in an organically certified crop.

Common name			Amount/Acre**
(trade name)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies. Also consider information relating to water quality when choosing a pesticide.
BEFORE PLANTING
A.	THIAMETHOXAM
	(Cruiser) 5FS
	MODE OF ACTION: A neonicotinoid (Group 4A)1 insecticide.
	COMMENTS: A seed treatment. Use allowed under a supplemental label. Do not apply other neonicotinoid (Group 4A) insecticides within 45 days of planting seed treated with this product.
B.	CLOTHIANIDIN
	(Poncho)
	MODE OF ACTION: A neonicotinoid (Group 4A)1 insecticide.
	COMMENTS: A seed treatment. Do not apply other neonicotinoid (Group 4A) insecticides within 45 days of planting seed treated with this product.
C.	DIAZINON* 50W		4–8 lb/acre
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Broadcast before planting; incorporate to a 2-inch depth immediately. Avoid drift and tailwater runoff into surface waters.
** Mix with sufficient water to obtain full coverage. * Permit required from county agricultural commissioner for purchase or use. 1 Modes of action are important in preventing the development of resistance to pesticides. Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode of action is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

PUBLICATION

UC IPM Pest Management Guidelines: Corn
UC ANR Publication 3443
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
S. D. Wright, UC Cooperative Extension, Tulare County
C. G. Summers, Kearney Agricultural Center, Parlier
C. A. Frate, UC Cooperative Extension, Tulare County
Acknowledgement for contributions to the Insect and Mites section:
M. J. Jimenez, UC Cooperative Extension, Tulare Co.

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