How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

Grasshoppers can be occasional pests of corn. In late summer and fall, grasshopper eggs are laid in grassy foothills, on ditch­banks, along roadsides and fence rows, in pasture areas, and in alfalfa fields. Eggs hatch in spring and young nymphs feed on nearby plants. When wild grasses and other plants become dry, grasshoppers migrate to irrigated croplands.

DAMAGE

Grasshoppers feed on foliage, most often on the edges of fields near pasture areas or roadsides. They seldom cause economi­cally significant injury.

MANAGEMENT

Topical treatments are most effective; treating field borders may be adequate.

Common name		Amount/Acre**	P.H.I.+
(trade name)			(days)
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.
A.	CARBARYL*
	(Sevin) 80S, XLR Plus	10–24 oz	Sweet corn: 2
			Forage: 14
			Fodder: 48
	MODE OF ACTION: A carbamate (Group 1A)1 insecticide.
	COMMENTS: Ground or air application.
B.	MALATHION 8E	1 pt	Harvest or forage: 5
	MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
	COMMENTS: Limited residual effectiveness.
	** Mix with sufficient water to obtain full 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: 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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