Jeff Edwards Discusses Management Practices for Lodged WheatFri, 06 Apr 2012 14:18:13 CDT
Recent storms have resulted in lodged wheat around the state of Oklahoma. In this article Small Grains Extension Specialist Dr. Jeff Edwards provides a few pointers on determining yield potential and management of downed wheat. He also addresses questions about physiological leaf speckling.
I have been getting several call and emails about lodged wheat. Wheat can lodge for several reasons including disease, insects, freeze injury, and excess fertility. Most of the lodging that has occurred this year is due to our warm winter combined with ample residual soil fertility caused by failed crops in 2011. The crop is thick with 3 - 4 times the normal number of tillers and is more susceptible to lodging from wind and/or pounding rain.
Will the lodged crop stand back up?
Maybe. It depends on the severity of the lodging. Wheat that is completely flat on the ground with a broken stem will generally not recover. The plant will attempt to go ahead and fill grain, but will not be very successful. Wheat that is partially lodged prior to grain fill will generally make an attempt to “straighten up” and make some grain. There will be a yield penalty, but the crop will generally still make grain in the tillers that stand back up. Wheat that is simply leaning will still have full yield potential.
Should I spray a fungicide on lodged wheat?
This is a tough one. I would not spray fungicide because the wheat is lodged. It is true that the mat of lodged foliage might be more conducive to disease; however, if wheat is lodged this severely, light penetration into the canopy for photosynthesis, and not disease, will be the primary yield-limiting factor. If I had already made plans to apply a fungicide and the wheat lodged prior to making the application, I would use the information in the previous paragraph to help determine my remaining yield potential and make the fungicide call based on yield potential at the time of application. Fungicides will not help the wheat “stand back up”.
Physiological leaf speckling
I have gotten a few questions on yellow spotting on wheat leaves. If you find active rust pustules on leaves, it could be part of the plant reaction to leaf or stripe rust. In many cases, however, it is what is termed “physiological leaf speckling” (also called physiological leaf flecking or spotting). We have experienced this off and on with the varieties Doans and Duster and the speckling was severe in 2007. Jagger, Fuller, and the new OSU variety Gallagher are also showing some physiological leaf speckling this year.
Unfortunately, this is a phenomenon that is not well understood. What we do know is: it is not disease related so fungicides should not affect the severity and although it looks similar to chloride deficiency, in most cases it is not. The things we don’t have a good handle on include: how much, if any, it will affect yield and what set of environmental conditions are conducive to the onset of physiological leaf speckling.
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