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Scout alfalfa for weevils and aphids

May 25, 2023 7:54 AM
Blog Post

Alfalfa growth is off to the races in many parts of Iowa, and we have heard reports from around the state that insects are very active in alfalfa as well. Field agronomists, especially in southern Iowa, have reported that hay is being cut early due to alfalfa weevil pressure, and they are seeing quite a few aphids as well. If you have not yet done so, consider scouting alfalfa for these pests to ensure that a timely management decision can be made.

Aphids Showing up in Alfalfa

May 18, 2022
Common aphids in Iowa alfalfa.

Aphids are common insects to see in field crops, especially in alfalfa. In Iowa, there are at least four aphid species that colonize this crop. A quick scouting bout in central Iowa yesterday (May 17) revealed at least two species feeding within the same field. Learning to distinguish aphids in alfalfa takes a little practice, but is worth knowing for making sound treatment decisions.

Scout Crops for Aphids

August 19, 2013
Soybean aphid density test

Soybean aphid

This is the only species in Iowa that will colonize soybean. Scout weekly from plant emergence until seed set. Aphids prefer to feed on the undersides of leaves and will establish on the newest leaves. If a large colony develops, they will feed on stems. Initial infestations are patchy and located near field edges, but winged aphids can quickly disperse within and between fields. Commercial fields that have reached uniform infestation should be closely monitored in August.