David Owens, Extension Entomologist, owensd@udel.edu
Alfalfa
Scout for potato leafhopper. There are reports from states to our north that potato leafhopper are causing significant hopperburn. Remember, if you see yellowing, yield has ALREADY been impacted. There are dynamic thresholds for potato leafhopper in our alfalfa insect control guide (adapted from Penn State): https://www.udel.edu/content/dam/udelImages/canr/pdfs/extension/sustainable-agriculture/pest-management/Insect_Control_in_Alfalfa_-2020_-_David_Owens.pdf.
Field Corn
Pay attention to field edges for brown stink bugs, especially those around drainage ditches and previous small grain fields. Thresholds for them start increasing as we move into the silk stages. Concentrate your scouting activity around the ear zone. Count the number of bugs per 100 plants. Thresholds can be found here: https://corn.ces.ncsu.edu/stink-bug-management-in-corn/.
Japanese beetles are active and may be seen clipping silks or feeding on foliage. Silk clipping is only a concern if silks are clipped to less than ½ inch before 50% pollination and there are 1-2 beetles per plant. It is very unusual for all three of these conditions to be met.
Soybean
Dectes stem borer has begun emerging and will be active for the next 5 weeks. Full season fields planted early are in the early reproductive stages. Scout for stink bugs, thresholds are 5 bugs per 15 sweeps. I will hold a virtual soybean insect identification review Monday, July 19 starting at 7:30. You can connect by zoom: https://udel.zoom.us/j/5682701927. Also, if you insect identification questions, you can send them ahead of time to owensd@udel.edu.