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How much has drought affected your crop?

Published: Friday, Sept. 13, 2013 5:50 p.m. CST

As the agriculture community in northern Illinois prepares for a harvest that has been hastened to maturity by late season dryness and high temperatures, a recurring question arises when I visit with farmers whose corn is brown instead of green. “What impact will this have on final yield?”

The Sept. 10 U.S. Drought Monitor places all of Bureau County in either the abnormally dry or moderate drought categories. I had hoped this question would not arise again, especially on the heels of 2012, but a year later we are experiencing similar weather patterns. What will benefit growers greatly is this has been a comparatively short term event compared to the almost season-long drought last year.

To answer the question if we can still lose yield when our corn is at full dent, (R5) I’d like to share the perspective of Bob Nielsen from Purdue University. In a Sept. 10 news release he shared the following information:

“Once corn reaches dent stage, many folks can be heard confidently stating that there is no reason to worry about further crop stresses because the crop is made, Actually, by the time a crop reaches full dent, only about 60 percent of the crop has been ‘made,’ and there is still 40 percent of the potential yield on the table yet to be determined. In fact, corn plants can still fall victim to sudden and complete death as late as two weeks before physiological maturity if conditions are bad enough. Whole plant death can translate to yield losses as high as 12 percent.”

To ground truth this assumption Emerson Nafziger, University of Illinois agronomist, oven dried and weighed kernels from a trial at the U of I campus. The kernels were collected at beginning R5 (full dent) and 10 filling days (about 250 GDD) later. In his summary of the kernels collected on the second date Nafziger shared, “the milkline – the separation between hard and soft starch – was about halfway down the kernel. According to the Iowa State University publication ‘Corn Growth and Development’ (PMR 1009), kernels at a half milkline have accumulated about 90 percent of their maximum dry weight, are at about 40 percent moisture, and have about 200 GDD left to go before maturity. These kernels weighed 306 mg, or about 83,000 kernels per bushel, and they were at 31 percent moisture, which is considered typical for grain at physiological maturity. Thus it’s likely that these kernels were at or very close to their final weight.”

While this was a singular evaluation, it is a good news scenario as it suggests the hybrid was able to reach near maturity in a shortened time frame in this year’s conditions. Emerson’s article in its entirety can be accessed at http://bulletin.ipm.illinois.edu/?p=1681.

The final yield is not attained until a corn crop reaches physiological maturity or “black layer,” the darkened layer of cells at the tip of the kernel that indicates the tissue that transfers sugars into the kernel is no longer active. At this point the kernels have attained their maximum dry matter accumulation. We expect growers in portions of northern Illinois to have lost potential yield due to the shortened grain fill period, but just how much or little, will be answered when the combines start rolling.

If it appeared that your corn “matured” almost overnight, be aware that corn plants placed in this stressful situation will cannibalize stored carbohydrate reserves from lower stalk and leaf tissues and move them to developing ears. This can weaken stalks and increase the risk of root and stalk rots.

The Bureau, LaSalle, Marshall and Putnam Counties Extension office has several upcoming events including:

Oct. 3 – U of I Extension, along with Illinois Stewardship Alliance, Illinois Farmers Market Association and the National Sustainable Agriculture Coalition will present a webinar covering the FDA Food Safety Modernization Act (FSMA). The webinar will run from 3 to 4:30 p.m. There is no charge for the webinar, but registration is required. Topics covered in the webinar will include:

Introduction to the Food Safety Modernization Act (FSMA), Deborah Cavanaugh-Grant, local food systems and small farm educator, U of I Extension

Preparing for FSMA: Good Agricultural Practices (GAPs) and On-Farm Food Safety Plans, James Theuri and Ellen Phillips, local food systems and small farm educators, U  of I Extension

In-depth Overview of FSMA (including Tester-Hagan Amendment and other local food and organic-related amendments), Wes King, interim executive director, Illinois Stewardship Alliance

How to Get Involved: the Federal Register Comment Process and Resources for More Information, Sarah Hackney, grassroots director, National Sustainable Agriculture Coalition

U of I Extension offers this webinar and other GAPs training to help growers identify areas of high food contamination risk, particularly with infectious microbes, and prepares the growers to write a food safety plan.

“We help them with writing safety plans and, if requested, follow with mock audits of their farms in preparation for the real audit,” added Extension educator James Theuri.

Register online at https://webs.extension.uiuc.edu/registration/?RegistrationID=8819 or call 217-782-4617.

Dec. 3 - The Bureau, LaSalle, Marshall, Putnam Unit will be providing Pesticide Safety Education Training and Testing this fall and winter.

Dec. 9 - The first of five Test-Only sessions will be in Bureau County at the Extension Office.

For those visiting the Bureau County Homestead Festival this weekend, don’t miss the lunch at the Bureau County Pork Producer’s Tent. Funds raised go to support the Bureau County 4-H and Extension programming; many thanks to our supporters.Best wishes on a bountiful and safe harvest.

Russ Higgins is from the University of Illinois Extension, Northern Illinois Agronomy Research Center.

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