INFO-BUG

Crop Selected: Field Corn
Crop Development: Tassel or silk stage
Pest Selected: Corn leaf aphid, Rhopalosiphum maidis

Biology

Colonies of blue-green aphids begin to appear on corn during the late whorl stage. If abundant, they may cause stress to the plant especially under drought conditions.

The aphids secrete honeydew, and heavy population activity may inhibit pollen shed as the sticky honeydew inhibits dropping of pollen.

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Corn leaf aphids

Assessment

As corn enters the late whorl stage, activity of aphids should be monitored, especially under dry weather conditions.

If significant number of aphids are noted on 50% or more of the plants, a rescue treatment may be warranted.

In general, the severity of the aphid colonies on the corn is directly related to the proportion of corn plants infested.

Beneficial insects often control aphid infestations. Thus, the need for treatment is seldom justified unless the plant is under significant stress.

Control

Treatments labeled for control of CLA on corn include the following:

- Asana* @ 5.8 to 9.6 fl oz/A
- Capture* @ 2.1 to 6.4 fl oz/A.
- Dimethoate @ 1/3 to 1/2 lb a.i./A
- Lannate* @ 0.23 to 0.45 lb a.i./A.
- Lorsban* 4E @ 1/2 to 1 lb a.i./A.
- malathion @ 1 lb a.i./A.
- Mustang* @ 2.9 to 3.4 fl oz/A.
- Penncap-M* @ 1/2 to 1 lb a.i./A.
- Warrior* 1CS @ 2.56 to 3.84 fl oz/A

Note: Natural enemies generally provide sufficient control of aphid infestations.

* Use is restricted to certified applicators.

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