Friday, May 28, 2010

Now Is The Time to Look for Foliar Disease in Your Grain Crop

by Steve Hines, Extension Educator

This spring weather has been a challenge so far to say the least. Colder than normal temperatures, freezing at night, and lots of wind have created some interesting conditions for plants to grow in. While much concern has been focused on sugar beets, early planted corn, and preparation for beans, the cereal grains have been in the ground and on the back burner for awhile.

In the spring of 2005 we saw conditions somewhat like this spring with cold temperatures and plenty of moisture. While we haven’t had quite the moisture yet this year, the last few years have indicated that May and June can be wet months.

If you have grain in your crop rotation it may be worth some time to spend a few minutes walking those fields and looking for early indications of foliar diseases. In irrigated country we don’t need the rain moisture. By irrigating we create a humid micro-environment artificially, especially with sprinklers.

Cool weather and high humidity are factors that can lead to foliar disease outbreaks. Normally by the time I get a call about these diseases, the grain crop is at or past the flag leaf stage and there is nothing that can be done economically at that point. Just because you have a foliar disease is no reason to call the applicator either. You need to make sure the disease is properly identified and then determine if it is at or above the threshold level. Most of our grain crops are going to have some foliar disease.

Hot, dry, windy conditions prevent the spread of foliar diseases and our warm dry conditions do that fairly well.

In the eastern part of the US it is common practice to apply a fungicide as part of normal farming practices. Western growing conditions aren’t the same. Spend some time each week between now and the boot stage looking for the presence of foliar diseases. You want to look for leaves in the upper canopy that are yellowing or have gray, brown, black, orange, or yellow splotches or spots. Keep in mind the very lowest leaves are going to be yellow or brown as they die back naturally. Pay attention to determine if any abnormality found is in an isolated area or spread across the field. Foliar diseases are not uncommon in the Magic Valley, but they don’t often reach levels where fungicide applications are necessary.


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