How to Manage Pests

UC Pest Management Guidelines

Wireworms are beetle larvae that are found in soil where they feed on seeds and roots. They are shiny, slender, cylindrical, hard-bodied, yellow to brown larvae that can be found at all times of the year and in almost any kind of soil. The larval (or wireworm) stage may last several years. When fully developed, wireworms vary in length from about 0.5 inch to 1.25 inches, depending on the species. Adults are known as click beetles. They can snap and flip their bodies into the air when turned upside down. The tan to black beetles vary from 0.25 inch to more than 1 inch in length, but the most common pest species are about 0.5 inch long.

Wireworm larvae injure crops by partially or completely devouring seeds in the soil, thus reducing plant stands. On plants, they can cut off small, underground stems and roots or bore into larger ones.

MANAGEMENT
Cultural Control
Minimize plant residue from previous crops. Crops following pasture, alfalfa, vineyards, and grains may develop high populations of wireworms and require preventative treatment. Fallow fields for several weeks to allow organic matter to decompose. Seeds planted at depths greater than 1.5 inch take longer to germinate and are at greater risk for infestation. Do not plant into cold, moist soil.

Organically Acceptable Methods
Cultural controls are acceptable for use on organically grown produce.

Monitoring and Treatment Decisions
If wireworms have been a serious problem in the past, a preventative treatment may be necessary. Preplant or seed treatments are far superior to any postemergence practice.

Common Name		Amount/Acre**	P.H.I.+
(trade name)			(days)
When choosing a pesticide, consider information relating to water quality, insect resistance, and impact on natural enemies and honey bees.
PREPLANT
A.	DIAZINON*
	(Diazinon) 4E	3–4 qt	14
	(Diazinon) 14G	21–28 lb	0
	(Diazinon) AG 500	3–4 qt	14
	(Diazinon) AG 600WBC	76.5–102 oz	14
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: For wireworms broadcast insecticide just before planting and immediately incorporate into the top 4-8 inches of soil. Avoid drift and tailwater runoff into surface waters.
B.	METAM SODIUM*
	(Vapam, etc.)	Label rates
	COMMENTS: Apply as a band treatment before planting. Fumigants, such as as metam sodium and 1,3-dichloropropene, are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available.
** Mix with enough water to provide complete coverage + Preharvest interval. Do not apply within this many days of harvest. * 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: Spinach
UC ANR Publication 3467
Insects and Mites
W. E. Chaney, UC Cooperative Extension, Monterey Co.
M. LeStrange, UC Cooperative Extension, Tulare Co.

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