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Ohio State University Extension


C.O.R.N. Newsletter 2009-37

Dates Covered: 
October 27, 2009 - November 10, 2009
Curtis E. Young

Winter CORN Newsletter Schedule.

After this issue of the CORN Newsletter, our publishing schedule will be shifting to the off-season winter schedule with a reduced number of monthly newsletters. The next issue of the CORN Newsletter will be published during the week of November 9, 2009. For the next couple of months there will 2 issues of the CORN Newsletter published per month with two issues in November, 2009, December, 2009, January, 2010, and February, 2010, three issues in March, 2010, and a return to weekly issues again in April, 2010.

Get Grain Tested for Mycotoxin before Making a Decision

As corn harvest continues to lag behind schedule, concerns about mycotoxin contamination of grain continue to increase. Some growers are already asking whether they should abandon their field because of potential mycotoxin problems. As we indicated in one of our recent newsletter articles, conditions have been favorable for ear rot development and mycotoxin accumulation, and we have received reports of these problems occurring in some areas. However, the problem is not widespread across the state.

Favorable weather and harvest conditions for mold development mean that the risk of having the problem increases, but does not guarantee that the problem will occur at high levels in every field. In addition, even if ear mold develops, it may not affect the entire field and may not lead to mycotoxin contamination. Favorable weather conditions must be accompanied by a susceptible hybrid and the right pathogen for ear mold (or any other disease) to develop and grain contamination with mycotoxin to occur. Remember not all ear molds lead to mycotoxin contamination and some hybrids are more resistant to the ear rots than other. This link provides more information on ear molds and mycotoxin contamination

Before making a decision, walk fields and examine multiple ears for ear rot. If you find ear rot and have problems determining if it is one that leads to mycotoxin contamination, contact your county extension educator or send samples here to our lab for identification (1680 Madison Ave., Wooster, OH, 44691). If you find ear rot and know for a fact that it is one that could lead to mycotoxin problems, try to determine how widespread it is in your field. Examine between 50 and 100 ears at multiple locations spread out across the field…the more the better. One ear with ear rot out of every 100 ears is not a widespread problem. However, if about 10-15% or more of the ears (5-7 out of 50 ears or 10-15 out of 100) have more than 25% moldy kernels, a sample of the grain harvested from that field should be sent to a lab for mycotoxin testing before feeding to animals.

In the case of aflatoxin, the BLACK LIGHT test is often used to identify positive samples. However, a positive test (fluorescent color observed) only provides preliminary indication that aflatoxin may be present and does not automatically mean that the grain is highly contaminated. Other compounds in the grain or other fungi may cause grain to fluoresce, leading to a positive BLACK LIGHT test. Again, the presence of the fungus and a positive test do not always mean that toxin is present. On the other hand, grain testing negative for aflatoxin based on the BLACK LIGHT test may still be contaminated. If samples are older than a few weeks, the test may give negative results even when aflatoxin is present. FRESH samples should be used for this test. After this preliminary test, grain should still be sent to a lab for testing.

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Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.