Agronomy Talk

Agronomy Update

Burndown Escapes

Published on Monday, April 4, 2016

The warm weather we’ve been experiencing has given farmers the opportunity to get out and start getting fields ready for planting. I wanted to address some issues I’ve seen this year concerning volunteer wheat and ryegrass escaping burndown applications.

The warm winter we had provided these weeds ample opportunity for growth and as we all know, the bigger the weed the harder it is to control. A common burndown program in the south is Roundup® + dicamba. While this is usually a very good program, it can leave room for survivors to make it through. Dr. Larry Steckel, UT Extension Weed Scientist, wrote an article a few years back describing how dicamba can sometimes antagonize the grass control of glyphosate. This is not always the case, but on bigger, tougher weeds (volunteer wheat and ryegrass) it sometimes shows.


Photo Credit: Dr. Larry Steckel

If these weeds powered through the first burndown, they become much more difficult to control. Once they are injured and show some phyto-toxicity, they will not translocate another systemic herbicide very well. This means you will likely need to shift your approach to a contact type herbicide. Dr. Steckel has seen a good response with Gramoxone® + Atrazine + Crop Oil.

On another note, I wanted to touch on wheat herbicides and their cut-offs. Most of our wheat is looking very good and I’ve seen very little disease pressure so far. With the warm winter and the range of planting dates we had in the fall, the maturity stage of our wheat varies greatly. I’ve walked some fields that are in the “boot stage” and some that have just began jointing. It is very important to stage your wheat before you make a herbicide application because there are specific cut-off restrictions. For example, metribuzin, dicamba, PowerFlex®, and Osprey® should not be applied past the first node, however Harmony® can be applied past the 2-leaf stage but prior to flag leaf.

With commodity prices down it can sometimes be difficult to justify herbicide applications. But remember, cool-season annuals can decrease wheat yields by approximately 10 percent.

Roundup® is a registered trademark of Monsanto Technology, LLC. Gramoxone® is a registered trademark of a Syngenta Group Company. PowerFlex® is a registered trademark of The Dow Chemical Company (“Dow”). Osprey® is a registered trademark of Bayer CropScience LP. 


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Austin Scott

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