Our black light traps are showing low to very low levels of western bean cutworm moths, European corn borer, and corn earworm, especially compared to the levels we were finding this time last year. We have found a few corn leaf aphids on some of the heavier ground in our area so be sure to be monitoring your fields for this pest as the summer progresses. Much of the corn in our area is at the tail end of pollination and is looking good. Low levels of rust can be found in most all of the fields in our area. Anthracnose leaf spot is common in fields that are corn after corn. We have only found a few fields with trace amounts of Northern corn leaf blight to date, but with wet weather on the forecast it is likely to spread.
Japanese beetle, green clover worm, aphids have been the main insects we have been finding these past few weeks, but no fields have reached economic thresholds yet. Be vigilant in scouting for aphids as the extended forecast of cool weather will be very conducive to aphid reproduction. University thresholds are 250 aphids pre-plant which may sound like a lot, but when the population can double every few days it does not take very long for a field to become infected. Septoria brown spot is slowly building in the lower canopy of many of the soybean fields in our area. Consider a foliar fungicide if you have moderate or heavy disease pressure at this time. The key time for fungicide on soybeans is the R1 (beginning flower) to R3 (beginning pod) stage. Many of our fields are in the R3 stage to R4 (full pod).
Late blight continues to be a problem and is slowly but surely spreading with each week, bringing one or two more fields found to have been infected. So continue to apply fungicide on your scheduled interval being sure to add premium late blight material especially on the weeks of cool wet weather like we have been having. We are currently in the midst of second generation Colorado potato beetles with adults already laying eggs and larvae hatching. Some of the petiole numbers are starting to crash as the crop begins to pour energy into the tubers. We have been checking tubers for shape and size last week and this week to see if an MH30 application is needed to correct the shape of the tubers.
– Otto Oemig, Agronomist