Agronomic Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Small Grains
Armyworm larvae were intercepted in low numbers this week by consultants. Thresholds are fairly high, 1-2 per square foot. Be sure to also examine residue if scouting during the day, as caterpillars like to hide.

Soybean
Please see the note in the vegetable scouting section on seedcorn maggot. It is possible that we will have an elevated seedcorn maggot activity period coming up this week. Soybeans planted into tilled fields, especially those with a cover crop and/or manure should have an insecticidal seed treatment on them. Pay attention this week to emerging soybean in no-till conditions for signs of slug damage. Soybean stands can get thinned out quite a bit before soybean begins losing yield. It is also very difficult to time a bait application. Often times, once plants begin to emerge, slugs may have done enough damage to render that application a revenge only type of situation. Slug bait is most effective when applied following wet weather but with dry weather afterwards.

Alfalfa
There are still some alfalfa fields above weevil threshold. Be sure to measure alfalfa as it may be approaching a height for which early cutting may be an option. If cutting and baling, be sure to scout the regrowth to make sure that alfalfa weevil is not working on it. Please note that chlorantraniliprole is ineffective on weevil larvae, thus Besiege provides no additional benefit over a lambda-cyhalothrin alone product such as Warrior II or generics. Please also note that as alfalfa continues growing, thresholds drift up a bit.

Early Season Moth Activity
Many thanks to Haley Sater with UMD Cooperative Extension and Joanne Whalen, Extension entomologist emeritus extraordinaire for assistance with checking traps. Moth counts were a bit lower this week, but still catching fair numbers of black cutworm and high numbers of true armyworm in Smyrna.