1. Field Observations and Weather Outlook

More corn tasseling this week, so in addition to checking crops for disease, now is the time to scout for corn rootworm if you're hoping to plant corn into that field again next year. The threshold for Western corn rootworm is roughly 1 per plant, while the threshold for Northern corn rootworm is 2 per plant. See the image below for ID (from South Dakota State Univ. Ext). Here is a video tutorial on corn rootworm scouting from NYSIPM: IPM for Corn Rootworm on Field Corn.

Silage corn needs 750-800 GDD (depending on hybrid maturity) after silking to reach a whole plant DM of 32%. Under typical late season dry down conditions we can expect the crop to reach 35% DM four to seven days later. We can expect to accumulate 20-25 GDD per day, or even up to 30, so peak maturity can creep up on us quickly. But no matter what the numbers say, always check your crop to see how close you may be to harvest. For more details, see this article.

Soybeans are entering R3, so we're nearing the end of the window for protecting crops from white mold risk.

And once again, enjoy this new spell of dry weather while we have it!

2. Growing Degree Days (GDD) (See: Climate Smart Farming Growing Degree Day Calculator)

Growing degree days (GDD) are calculated by taking the average daily temperature and subtracting the base temperature for development of a given organism ((High + Low)/2 - base temp = GDD). For corn silage, we are using base 50/86, as corn development starts at 50 degrees F and ceases above 86. Check your location and planting date:

3. Pest Monitoring

New growth of new seedings of alfalfa tended to be above threshold for potato leafhopper this week (Table 1). Western Bean cutworm and Fall Armyworm are increasing, but I still have yet to see egg masses or larvae in any of these locations (Table 2). I have not seen soybean aphid issues so far - populations are very low.

Table 1. Potato leafhopper scouting:

Table 2. Corn moth trap data