Jim Schwartz, CCA 
ICORN IGRONOMIST
1-800-240-0101
jschwartz@icorn.com

 New weather update

 Foliar diseases showing up

Root development in corn

Checking for Corn Rootworm

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New weather update

Here are the new weather numbers.  Most of us are still behind on GDU’s and it will be difficult to catch up in the summer because you typically max out most every day, every year, so it’s real tough to gain on the average. Keep in mind that last weeks rainfall totals do not include all the rains from July 4-6 .

Foliar diseases showing up

I have noticed some foliar diseases showing up in fields, including Rust (common rust I think), Gray leaf spot, and some Northern Corn leaf blight.  Most of these diseases have appeared because of the favorable conditions which include high humidity and ample moisture.  The good news is that many of these diseases require similar conditions in order to produce more spores and continue the spread of the disease.  Also, most hybrids have pretty good resistance built into them.  The exception is Gray leaf spot so keep a close eye out for these diseases.  Here is a link from Purdue. Pest & Crop

Root development in corn

I found this article on root development in corn by Dr. Peter Thomison of Ohio State and thought it might be of interest to you.  It also saves me the time typing up something similar.
Assessing Corn Root System Development - Thomison

Checking for Corn Rootworm

Now is the time to get out and dig corn roots and check for rootworm feeding damage.  Go out and dig (not pull) several plants and carefully wash the roots and look for brown feeding scars or roots that are pruned back.  Don’t forget to go check some of your first year corn if you live in East-Central Illinois, Northern Indiana or Northwest Ohio to be sure that the Western Corn Rootworm variant that lays its eggs in soybean fields has not found you.

Also, if you live in these areas, it’s a great idea to put out some sticky traps in your soybean fields to find out if you have high numbers of Rootworm adults in your soybean fields.  Right now through the first week or two of August or right before silking is a great time to put out these traps.  Place four or five traps in any given field and replace them every week to 10 days.  Record the number of beetles on the trap and whether they are Western, Northern or Southern Rootworm adults.  It is still difficult to correlate numbers as a predictor of problems next year but I have some links that will help you make the determination, its good information.  Call with any questions about this issue or if you need any help finding the traps or how to use them.

Managing Corn Rootworms - 2003

Rootworm variant wriggles free of rotation control

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