INFO-BUG


Crop Selected: Soybean
Crop Development: Pod-set to maturation

Biology

Pests Selected:

Differential grasshopper Melanoplus differentialis
Redlegged grasshopper M. femurrubrum

Grasshoppers occasionally build up to high numbers in soybean fields to the point that they may cause significant foliar damage and pod damage. A rescue treatment may be required.

Grasshopper

In general both the adults and nymphal stages congregate along the field perimeter especially near fencerows and ditch banks.

As the season progresses, they move into soybean fields with peak activity occurring in late August or September.

Assessment

Since grasshoppers contribute to the general defoliation level, the economic threshold is the same as that given for other foliar feeding insects, namely: 40% prior to bloom, 15% from bloom to pod-fill, and 25% from pod-fill to plant yellowing.


| Click to see defoliation levels on leaves: |

The most important aspect in assessment of grasshopper injury is to obtain a representative defoliation sample since damage is often concentrated at the field perimeter.

In the late summer and fall, pods should be examined. If 8% or more of the pods are damaged and pests causing damage are present, then rescue treatment is warranted.

Control

Where grasshoppers are a significant problem in soybeans, recommended rescue treatments include the following:

-
Material PHL (1)
Asana*21
Dimethoate21
Furadan*21
Lorsban* 4E28
Malathion21
Mustang*7
Penncap-M*20
Scout X-Tra21
Sevin21
Warrior*45
(1)Note preharvest limitation if late season treatment applied.

* Use is restricted to certified applicators


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