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Northern Illinois Agriculture

University of Illinois Extension
Minimum temperatures Sept 2014

Effect of cooler weather

Posted by Russel Higgins - Weather

Northern Illinois farmers are waiting for favorable weather to insure the 2014 crop reaches maturity and initiates dry down. The National Agricultural Statistics Service report shared that for the week ending September 14th; 92% of the corn was dented with 29% mature in the NW crop reporting district. 81% of the corn was dented and 8% was mature in the NE crop reporting district.

And the recent cool weather? We just experienced several unseasonably cool days, recorded minimum temperatures at the Northern Illinois Agronomy Research Center were below 40 degrees on September 12, 13 and 14.  What effect, if any, may this have had on our crops? Corn withstands late season cool weather better than soybean. But cooler weather can affect the corn crop as well. According to Dr. Bob Nielsen, corn specialist at Purdue University when describing the 2009 growing season in no-till farmer, temperatures that reach 50 degrees or lower can be detrimental to the photosynthetic process.  Canadian researchers documented that photosynthetic rate in corn decreased by 18% to 30% the day following a cold temperature stress of about 40 degrees during grain filling.  Dr. Nielsen also shared that there is limited research that addresses the question on the effect of multiple days of cold temperature stress on photosynthesis and grain fill.

And soybean? Dr. Emerson Nafziger University of Illinois crops specialist has shared that cool temperatures can have a have a somewhat negative effect on soybean crop. Below-normal daytime temperatures (and clouds) mean less photosynthesis, and cool nights can physiologically limit growth rates and the photosynthetic rates the next day.

Hopefully the return to more normal temperatures will get the maturation and dry down process back on track in northern Illinois.

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