Timing is everything

by Dr. Jason Weirich for the September Today's Farmer

I think we can all agree that the 2015 growing season was one for the record books. In the past few years, parts of the MFA trade territory have had abnormal weather conditions, but this year it was widespread. Many of you didn’t get to plant all of your acres, and much of what did get planted was damaged. But Mother Nature doesn’t stop to account for our complaints, so it is time to think about next year.

This past spring I had several calls on how to burndown fields that were infested with a wide variety weeds.
A common theme on these calls was that the field didn’t have a fall-applied chemical program. As a result, the callers wanted to know how to kill 2- to 3-foot tall marestail and winter annuals. Before they could act on that recommendation, it rained again.

The next call was, “How do we kill marestail and giant ragweed and pigweed.”

Sooner or later, with that kind of pressure, the best response was, “with steel.” But, as you know, this spring’s weather put producers in a difficult spot. You couldn’t get into the field to till, at least not in a timely manner.

The point is, in many cases, a fall-applied herbicide program might have been beneficial. When it comes to fall-applied herbicides there are a lot of different thoughts and theories on what makes the best program for each acre. Fall-applied chemical programs are not one-size-fits-all.

First off, fall-applied chemical programs aren’t being used to control waterhemp or Palmer amaranth. The purpose of a fall-applied program is to keep winter annuals controlled so next spring you can get in the field when conditions allow. Fall programs have little effectiveness on summer annuals. In some cases, you might see a residual effect on summer annuals, but it’s not enough to be considered effective weed control.

In a lot of calls I get, producers want to cut costs and use just a glyphosate/2,4-D mix as a fall program. While this program is effective at controlling weeds that have emerged, it doesn’t provide any residual for weeds that will germinate post-application and through spring.

Depending on the weather and germination of winter annual weeds, you may see significant germination after applying initial fall-program herbicides. That’s why I believe it is important to include a residual herbicide in the tank. This allows you to suppress winter annual weeds after application.

One of the main things you have to be aware of when planning a fall application is to account for the chemistries that you applied in the previous growing season.

It’s also important to ask, “What am I planting next year?” Each program comes with its limitations and restrictions. You don’t want to cause more headaches for next year’s growing season. I commonly recommend glyphosate, dicamba/2,4-D, and your choice of residual—depending on what crop you are rotating to next year. Always read and follow the label.

Not all fields are suitable for fall-applied herbicides. I don’t believe that highly erodible fields should be bare all winter. I would like to see some cover left on these fields to keep soil erosion at bay. Soil is a valuable resource. We don’t have the kind of time it takes to build it back.

If you have any questions about what specific herbicide program works on your farm, please contact your local MFA/AgChoice location for recommendations.

. . . . More from Dr. Weirich HERE

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