How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

Larva of the seedcorn maggot are small, pale or dirty-colored, yellowish white, legless maggots with tough skin. Adults are grayish brown flies and about 0.20 inch long. The sugarbeet root maggot larva is also a small, legless maggot with no distinct head or eyes. It is white in color and has two dark mouth hooks at the pointed end that are used for feeding. The adult fly is about the size of a housefly with a shiny black body with brownish spots at the base of the wings.

DAMAGE

Seedcorn maggots feed on the seed and may destroy it. Injury is most severe during wet, cold periods. Sugarbeet root maggots feed on succulent roots and cause plants to wilt and become stunted. Their feeding scrapes the root surface and may provide entry points for soilborne pathogens. They may sever taproots of small plants, causing plants to die.

MANAGEMENT

In California, seedcorn maggot and sugarbeet root maggot are only occasional pests. They are usually associated with high levels of organic matter in fields that have recently had a cover crop disked in. No treatment thresholds are available for sugarbeet root maggot; often problems with this pest are not apparent until plants begin to die.

Common name		Amount/Acre
(trade name)
NOTE: The following chemicals are registered for sugarbeet root maggot only. Currently there are no chemicals registered for the control of seedcorn maggot.
When choosing a pesticide, consider information relating to water quality and impact on natural enemies and bees.
A.	PHORATE*
	(Thimet) 20G	4.5 oz/1000 row ft
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Apply at planting; do not place granules in direct contact with seed. Do not feed tops to livestock.
B.	DIAZINON* 14G	7-14 lb or
		8 oz/1000 row ft
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Incorporate 2-3 inches or apply above seed after seed is covered. Do not allow granules to contact seed.
C.	CHLORPYRIFOS
	(Lorsban)15G	8 oz/1000 row ft
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: In-furrow at planting time. T-band or band at planting or postemergence.
*	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: Sugarbeet
UC ANR Publication 3469
Insects and Mites
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, Kern Co.
L. D. Godfrey, Entomology, UC Davis

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