Continue scouting for spider mites and cucumber beetles. Cucumber beetle pressure has been fairly light across the area. Thresholds are 2 beetles per plant. If your field is not at threshold, there is no need to put a pyrethroid in a fungicide tank mix, and that could possibly hurt mite management and flare up aphids. Also, bioassays conducted earlier this spring demonstrated rather poor results from the pyrethroids generally, except for Hero at its high rate. Spider mites continue to move into fields from field edges. If honeybees haven’t been placed, abamectin is a very efficacious miticide. Field edge treatments may also be quite effective at this time, provided no hotspots are detected in field interiors There is a lot of spider mite management information in a fact sheet written in part by Cody Stubbs and can be found here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/fact-sheets/two-spotted-spider-mite/
Our trap counts are now live and are updated by Tuesday and Friday mornings. You can find them here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/insect-trapping/.
One of the most frustrating facets about earworm control is early season worm development in whorls and tassels. Thresholds for tassel infesting worms are around 10-15%. If a cleanup spray is deemed necessary, we have several options including pyrethroids (especially with a Lannate tank mix), Radiant, Blackhawk, Intrepid and Intrepid Edge, Avaunt, and Vantacor. The advantage to avoiding a pyrethroid or a Besiege and Elevest is that impact to beneficial insects is minimized. Exposed worms, especially this time of year are much easier to kill than they are later in the season. I would prefer to hold off on a Vantacor, Besiege, or Elevest application to save the active ingredient for silk protection. If a Besiege application is made, adjust your rates such that you can get 2-3 applications during the silking period.
Thursday trap captures are as follows:
|3 nights total catch|
Continue scouting for Colorado potato beetle and potato leafhopper. Some questions came in earlier regarding European corn borer activity. Fortunately, ECB is highly attracted to corn, most of which expresses Bt toxins which have largely crashed ECB. For example, in Rising Sun, we have captured 6 moths over the last 7 years. Thresholds in potato are fairly high, with 10% of stems with tunneling. If CPB and potato leafhopper are not present and levels of concern, than no insecticide applications are necessary.
Begin scouting for signs of stink bug injury as well as spider mites. Thus far, very few stink bugs have been intercepted in our black light traps. In case you did not know, we do track stink bugs in blacklight traps. The data is uploaded at the same page where the earworm trap counts are. For stink bugs, the most effective materials are dinotefuran and bifenthrin.