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How to Manage Pests

UC Pest Management Guidelines


Grasshopper adult.

Corn

Grasshoppers

Scientific name: Melanoplus spp.

(Reviewed 1/06, updated 8/08)

In this Guideline:


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** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, information related to natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. CARBARYL*
  (Sevin) 80S, XLR Plus 10–24 oz 12 Sweet corn: 2
        Forage: 14
        Grain or fodder: 48
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: Ground or air application.
 
B. MALATHION 8E 1 pt 12 Harvest or forage: 5
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Limited residual effectiveness.
** Mix with sufficient water to obtain full coverage.
+ 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.
* 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

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 Insect and Mites:
M. J. Jimenez, UC Cooperative Extension, Tulare County

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