Field Crop Update, September 17, 2021
Erik Smith, Area Field Crop Specialist
Central New York Dairy and Field Crops
1. Field Observations
Not much to report this week as many folks are harvesting hay and silage, while soybean and picking corn are rapidly maturing. Here is the link to our recent webinar on things to keep in mind in advance of silage harvest if you're still on track to top-off your silos and bunks: 2021 Central NY Corn Silage Pre-Harvest webinar
As we talk about harvest timing and predicting whole plant dry matter, remember that prediction methods like growing degree days can only get you into the ballpark - there is no substitute for checking your crop to make sure you're harvesting at the right time. Please read the latest article from Joe Lawrence on this subject: Corn silage harvest timing: Not all growing degree days are created equal
And there is of course still time to plant your cover crops. The window to plant legumes is all but closed, but you can seed small grain cover crops into your now-empty fields for another few weeks. The following tables are adapted from: Rye cover crop mgmt:


And the following tables from NRCS Cover Crop Planting Specification Guide (New Hampshire, NH-340)


And once again, take note of problem areas in your soybean fields and let me know if you would like me to sample your field for soybean cyst nematode. This pest is widespread in NY, and I'm afraid that this year's wet conditions may have allowed them to spread more easily through infested fields. Sampling and analysis are free via grant funding from the NY Corn and Soybean Growers Association, though I am limited in the number of samples I can submit. So let me know.
2. Growing Degree Days (GDD) for planting date and silking date (Climate Smart Farming Growing Degree Day Calculator)
For corn silage, we are using base 50/86, as corn development starts at 50F and ceases above 86F. Silage corn needs 750-800 GDD (depending on hybrid maturity) after silking to reach a whole plant DM of 32%. Remember that we can expect to accumulate 20-25 GDD per day, or even up to 30, so this is not a large window. Under typical late season dry down conditions we can expect the crop to reach 35% DM four to seven days later. Check your crop to see how close you may be to harvest:

Not everyone planted their corn on one of the planting dates or in one of the locations I have listed, so this chart shows the estimated GDD for each location on each potential planting date in between (based on the actual GDD on those four dates). The locations are ordered top-to-bottom from lowest elevation to highest (the number after the location name is the elevation in feet above sea level). So if your farm is near one of the locations on this list but there's a location here that more closely matches your elevation, try that instead. You can find GDDs for your own specific location and planting date using the Climate Smart Farming CSF Growing Degree Day Calculator, but for those who might have more difficulty using that tool, maybe this chart can help.


Field Crop Update, September 17, 2021 (pdf; 1027KB)
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