How to Manage Pests

UC Pest Management Guidelines

Small Grains

Grasshoppers

Scientific name: Melanoplus spp.

(Reviewed 2/07, updated 2/09, pesticides updated 7/16)

In this Guideline:

DESCRIPTION OF THE PEST

Grasshoppers may occasionally attack grain crops, particularly if planted adjacent to foothill rangeland. They normally migrate from the range into cultivated areas as vegetation on the rangeland dries up.

DAMAGE

Grasshoppers destroy leaf tissue and, if present in extremely large numbers, they will consume the entire plant.

MANAGEMENT

Management Decisions

Since most grasshopper problems begin outside the grain field, areas favorable to grasshopper development should be carefully monitored for build-up and control measures taken if necessary.

Common name		Amount per acre	REI‡	PHI‡
(Example trade name)			(hours)	(days)
UPDATED: 7/16
The following are ranked with the pesticides having the greatest IPM value listed first&—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
A.	DIMETHOATE
	(Dimethoate 4EC)	0.75 pt	48	35
	MODE-OF-ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on wheat and triticale only. Do not make more than two applications per year. Do not graze within 14 days. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
B.	MALATHION
	(Malathion 8)	1 pt	12	7
	MODE-OF-ACTION GROUP NUMBER1: 1B
	COMMENTS: May be used on barley, oats, wheat, and rye. If alfalfa is in bloom, apply during the night or early in the morning when bees are not foraging in the field. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
‡	Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI; the longer of these two intervals is the minimum time that must elapse before harvest may take place.
*	Permit required from county agricultural commissioner for purchase or use.
1	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).

PUBLICATION

UC IPM Pest Management Guidelines: Small Grains
UC ANR Publication 3466

Insects and Mites

L. D. Godfrey, Entomology, UC Davis
V. M. Barlow, UC Cooperative Extension, Riverside County and UC IPM Program

Acknowledgment for contributions to Insects and Mites:

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