Field Crop Update August 22, 2026

A. Silage. This year's weather and extended planting window led to a similarly broad silking window in corn - so while most crops are still several weeks from silage maturity, some of the earliest acres may be approaching harvest in the next week or two, especially if those early acres have short RM. We had a slow start to the season, but we have had a lot of heat since silking - so be sure to stay on top of your crop. So with your silking dates in mind, take a look at Section 4. Growing Degree Days to see if you should be checking your whole plant DM soon. And don't be alarmed by the yellow locations/dates - those would be for those earliest acres.

Speaking of which, we are currently in the process of scheduling at least one (perhaps two) Corn Silage Dry Down events next month. So we will announce those dates and locations very soon (one will be at the Keystone Mills in Fonda, and the other is very likely to be at the CCE office in Madison County (Morrisville)).

B. Waterhemp. More and more, everywhere I look. Today we had a very informative waterhemp field walk in Dryden with Dr. Vipan Kumar, Cornell weed science professor. If you missed it (and even if you went), we'll be taking a deep dive into management strategies for this weed (and others) going forward at this winter's Central NY Corn and Soybean Day crop congress - save the dates: January 19th (central NY - venue TBD) and January 20th (Saratoga Co CCE) (stay tuned for more details and a registration link).

If you're organic, this is another pigweed to contend with, along with the other summer annuals with extended germination windows. But if you rely on herbicides, pre-emergents have to be part of the program for this weed - you cannot rely solely on post-emergents if you want ongoing management. And glyphosate does nothing. See the left side of the picture below for the full-rate glyphosate treatment at the recommended time.

At this point in the season, even spraying an effective herbicide is not likely to kill the plant (even if it isn't off-label to spray that given product at this point, which it very well could be!!). If you have a very sparse population, perhaps the first year of an infestation, it may certainly be worth it to pay some local kids to simply pull them out of the ground before they produce seed. Otherwise, each plant could produce half a million seeds, leaving you with a very difficult reality the following year after the harvester spreads those seeds everywhere.

Provided by Jessica Spaccio, Climatologist for the Cornell Northeast Regional Climate Center:

Western bean cutworm season is essentially past, but we will continue to watch fall armyworm - this time of year, they can overrun an alfalfa field.

Potato leafhoppers were all under threshold in the fields we monitored this week, while many other fields have been cut recently. So we don't have much to report this week. We will continue to monitor those fields through the month, though potato leafhopper numbers begin to decline in fall as they leave the region and overwinter in the southern states.

(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, we use base 50/86, as corn development starts at 50 degrees F and ceases above 86F. Check your location and planting date for grain GDD.

For silage, we track GDD from silking. Silking in our region began mid-July and is continuing through the first half of August. Your crop may have tasseled on or more closely to one of these dates. So while our GDD tables can get you in the ballpark, check your own whole-plant DM to make sure you’re ready, and not ahead/behind schedule!

Remember: 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 15-25 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. 

Silking date / silage forecast GDD color key:

Blue: Time to make plans (32-35% DM anywhere between 5 – 11 days from now, depending on maturity)

Green: Gas up the harvester and the trucks (32-35% DM in 2 – 8 days, depending on maturity)

Yellow: See you in the field soon (32-35% DM imminently)

Red: It’s either already in the bunk or it’s going for high-moisture corn or it’s going in the bin for grain (DM likely closer to 40%)