Pest Watch

Corn earworm

High captures continue, but not at more northerly sites.  

Many sites exceed thresholds (>10 moths/night) that suggest a three-to-four day spray interval, starting at early silk and continuing (if trap counts continue to be moderate to high) to about seven days prior to harvest. This occurred in at least one site in the following counties: Blair, Bucks, Centre, Lancaster, Lehigh, Lycoming, Mifflin, Montgomery, Washington, and York. Sites in Mifflin, Bucks and Montgomery approach or exceed thresholds suggesting a two to three day spray interval. It is not uncommon to apply five or more sprays to non-Bt sweet corn when pest pressure is this high. With Bt-sweet corn, growers in areas with the very high pressure are reporting clean ears with approximately two sprays.

Some northern and some higher elevation sites, however, continue to be low, and several locations are reporting a decrease. These moths fly at night and cooler nights will reduce flight activity. Flight stops at approximately 50 to 55oF. The low counts are in Erie, Lackawanna, Luzerne, Schuylkill, Lycoming, and surprisingly also in Franklin counties.

European corn borer

Counts continue to be low. Corn earworm sprays will cover whatever corn borers are out there.

Fall armyworm

are being detected, but not anywhere near damaging levels.

Other species to watch for

The summer generation of brown marmorated stink bug (BMSB), along with the green stink bug and harlequin bug is showing up. Some soybean fields are seeing high numbers of BMSB. Check edges of fields for stink bugs and their Pentatomid relatives, along with silk feeding, and sap beetles.

In summary, high corn earworm captures are continuing, but in fewer sites. There are notable exceptions with low counts, mostly in northern and higher elevation sites, but also Franklin County.

Meanwhile, stink bugs are also moving into vegetable crops.