Agronomic Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Soybean and Slugs
Some of the earliest soybean has been planted. The weather forecast is generally calling for cool weather with ample rain fall. Be watching these early fields like a hawk for slug damage. I am concerned that the April weather pattern we are in is very conducive to slug activity and feeding. We have been looking at fields throughout the state for slugs and slug egg hatch. All species are now active. Gray garden slug eggs have just begun hatching, but there are still quite a few eggs left to hatch. Avoid insecticides with cover crop burndowns, the only thing we are going to hit right now with them are predators that would be feeding on those slugs.

Small Grains
Cereal leaf beetles are active and should start laying eggs next week. The good news is activity reports are very low throughout much of the state. It will be important to look at tillers during the next two weeks counting eggs and small larvae. Eggs are typically laid on the upper one or two leaves, on the upper surface of the leaves, and near the midvein. Thresholds are 25 eggs/larvae per 100 tillers.

Alfalfa
Continue scouting for alfalfa weevil. Weevil larvae are light green and are best scouted for by beating stems into a bucket. At the same time, measure the stem length. If the stems are long enough, an early harvest is advised. More information can be found here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/vegetable-fruit-field/alfalfa/.

On another note, I found what looked to be a potato leafhopper in my garden. I don’t expect significant activity in alfalfa for another month or so, but with the warm winter we have had in the mid-Atlantic, it wouldn’t be a bad idea to periodically sweep