UC IPM: UC Management Guidelines for Wireworms on Cucurbits

UC Pest Management Guidelines

Cucurbits

Wireworms

Scientific Names: Limonius spp. and others

(Reviewed 11/05, updated 6/08)

In this Guideline:

Description of the pests
Damage
Management

Wireworms 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 of this insect may last several years. When fully developed, they vary in length from about 0.5 inch to 1.25 inches (12–31 mm), depending on the species. Adults of these larvae are known as click beetles. They can snap and flip their bodies into the air when turned upside down. These tan to black beetles vary from 0.25 inch (6 mm) to more than 1.0 inch (24 mm) in length, but the most common pest species are about 0.5 inch (12 mm) 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.

Preventive treatment may be warranted for crops planted in land that was previously pasture or planted to alfalfa, vineyards and possibly grains. Otherwise, good field sanitation and measures to ensure rapid seed germination are generally adequate for control of this pest.

Cultural Control
Minimize plant residue from previous crops. Fallow fields for several weeks to allow organic matter to decompose. Seeds planted at depths greater than 1.5 inch (3.7 mm) 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 to use in an organically certified crop.

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 postemergent practice.

Common name

Amount/Acre

R.E.I.+

P.H.I.+

(trade name)

(hours)

(days)

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 label of product being used.

IMIDACLOPRID

(Admire) 2F

16–24 fl oz

MODE OF ACTION GROUP NUMBER¹: 4A

COMMENTS: Apply at planting or transplanting and incorporate into root zone. Repeat applications of any neonicotinoid insecticide (imidacloprid-Admire; thiamethoxam-Platinum) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance.

DIAZINON*

(Diazinon) 14G

21–28 lb

MODE OF ACTION GROUP NUMBER¹: 1B

COMMENTS: Labeled for use on melons and watermelons only. Broadcast and incorporate into soil just before planting. May also control seedcorn maggot.

(Diazinon) 50W

4–8 lb

(Diazinon) AG500

2–4 qt

COMMENTS: Labeled for use on melons and watermelons only. Broadcast just before planting and immediately work into the soil 4–8 inches.

METAM SODIUM*

(Vapam)

Label rates

COMMENTS: Apply as a band treatment 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.

Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.

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 to help prevent the development of resistance. 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 Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

Permit required from county agricultural commissioner for purchase or use.

Not applicable.

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
L. D. Godfrey, Entomology, UC Davis
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
C. B. Fouche, UC Cooperative Extension, San Joaquin County
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/r116300411.html revised: September 23, 2009. Contact webmaster.

How to Manage Pests

UC Pest Management Guidelines

Cucurbits

Wireworms

Scientific Names: Limonius spp. and others

DESCRIPTION OF THE PESTS

DAMAGE

MANAGEMENT

PUBLICATION