Corn Maturity and Harvest Dates

        Although lack of rainfall through the course of the growing season has been a primary topic of discussion this year, a story of equal importance is the lack of heat.  Only 469 growing degree units (GDU's) were accumulated during the month of July.  This is 200 GDU's less than the 30-year average or the equivalent of 10 average summer days.  Killing frost date both here and throughout the Midwest is going to have a major influence on grain yield, market prices, and the cost of harvest or storage.  Recall that it takes corn 42 to 47 days to reach whole plant silage moisture from the time corn silks (see table).  It then takes an additional 10 to 15 days to reach physiological maturity (black layer or the point when dry matter accumulation in the kernel ceases).  Of course  there are a several environmental factors (e.g. temperature and soil moisture) that can either speed-up or delay maturity. 

        Once corn reaches reproductive stages (silking and beyond), the number of days becomes a bigger influence than the temperature.  Based on the previously discussed criteria, it doesn't look like much corn silage will be chopped until mid-September.  Further, if a frost comes early or the first one is a "stalk killer", there will be a significant number of acres that won't reach physiological maturity (black layer).

Corn Silage Dry-Down Days

        Corn silage growers will have several opportunities to test standing corn for whole plant moisture as fall approaches.  The Fond du Lac County Forage Council’s chopper will be set-up and open for business on Tuesdays, September 8^th, 15^th, and 22nd from 10 a.m. until noon at the Dave Schmitz farm located at N5236 River Rd., Fond du Lac.  The farm is located about one mile south of old Hwy. 151 (now County Rd. D). 

        Any Fond du Lac County resident or crop professional is welcome to bring stalk samples for testing on any of the above dates.  Bring four stalks per field (cut at chopper height) and have the following information readily available:  name, city/town, contact information (phone #, e-mail or fax), hybrid planted, hybrid relative maturity, and planting date.   It’s suggested that samples be cut from inside the field to avoid field border and headland effects.  Corn stalks will be chopped and taken to the forage lab for moisture analysis.  We will then contact you with this information as soon as it is received (usually the next day).    

Transgenics Have Become the Norm

        In the U.S. 85 percent of this year's corn acres were planted to a transgenic hybrid, a 5 percentage point increase from 2008.  Stacked gene corn hybrid use continues to increase, accounting for 46 percent of the national corn acreage in 2009.  Insect resistant (Bt) corn hybrid use was unchanged from last year, at 17 percent of the planted corn acres.  Herbicide resistant variety use decreased 1 percentage point from last year to 22 percent of the 2009 corn crop.  Herbicide resistant soybean variety use declined 1 percentage point from last year to 91 percent of the national soybean acres. 

        In Wisconsin, transgenic corn hybrids were planted to 77 percent of the corn acreage, up from 75 percent last year.  Stacked gene hybrids were planted to the majority of corn acres at 37 percent, while herbicide resistant corn hybrids make up 27 percent of the planted acres, and insect resistant hybrids 13 percent.  Herbicide resistant soybean variety use declined 5 percentage points from last year to 85 percent. 

Late-summer Alfalfa Seedings

        Seeding alfalfa in late summer is an excellent establishment alternative that will result in a stand that can be managed like an established stand next year.  These seedings also can be made where a small grain is harvested during July or early August.  As a rule of thumb, make late summer alfalfa seedings six to eight weeks before the first killing frost.  However, seedings can be made anytime during the month of August.  Keep your seed in the bag after September 1st. 

        There is no need to use a companion crop or pre-plant herbicide for weed control.  Weed pressure is not as intense during late summer compared to early spring. Additionally, warmer soil temperatures result in more vigorous development of the crop.  Companion crops are never recommended for summer seedings because they compete too strongly for available soil moisture.  Post-directed herbicides remain an option if weeds become too competitive; however, remember that the first frost will kill most annual weeds.  It's still important to control perennial weeds, such as quackgrass, before seeding the alfalfa.   

        Occasionally there is a need to control volunteer wheat where alfalfa seedings follow a winter wheat harvest.  This can easily be done using one of several herbicide options that are selective for grass species.