David Owens, Extension Entomologist, owensd@udel.edu
Corn
As planting time nears for corn, it’s important to know what your wireworm and white grub pressure is. This time of year, the easiest method is the compact soil sampling method. The compact soil sample consists of digging a hole 8 inches L x 8 inches W x 6 inches deep. Others (WSU.edu wireworm scouting fact sheet) recommend a shovel full, roughly 6 inches diameter and 10 inches deep with a treatment threshold of 1 wireworm every 5 shovel fulls.
This factsheet on white grubs explains the sampling strategy and has treatment threshold guidelines: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/2802/2802-7027/ENTO-296.pdf.
Small Grains
We have seen some signs that a few cereal leaf beetle may be present in fields, but have not yet seen adults. Aphid populations are building with the warm weather. Aphid species present are almost entirely English grain aphid. Due to crop prices, an insecticide during this period is not likely going to pay for itself.