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Delta Farm Press Palmer pigweed
<p> The most important factor in a pigweed control program is the application timing of the postemergence herbicides.</p>

Palmer pigweed - it's all about timing

Until Palmer pigweed control becomes the number one priority on your farm, you are going to lose.

Until Palmer pigweed control becomes a number one priority on your farm — whether you are eat up with pigweeds yet or not — you are going to lose.

There are a lot of important factors in a pigweed control program, but the most important is the application timing of the postemergence herbicides. When I went to work for the University of Arkansas in 1974, application timing was the number one problem we had in our weed control programs. In 2013, application timing is again the number one problem. That says a lot about how effective I have not been in trying to influence decisions!

Roundup Ready crops were a miracle. They were so good they spoiled us. They spoiled us by making application timing too easy and improper timing too forgiving. We have an entire generation of farmers that does not know any different, and it is not their fault.

Four challenges of herbicide-resistant weeds

That heyday is over, and it is all about timing again. If you can’t figure out how to get it done, the pigweeds will win and somebody else will be farming the land. The first step in application timing for pigweed control is to recognize what a 2-inch pigweed really looks like. Measure some if you have to. Now when you have done that, realize they should have already been sprayed.

Sometimes you can kill some bigger pigweeds with Flexstar, UltraBlazer and Liberty. But when you spray the larger weeds and kill a lot of them, take a look at how many 2- to 3-inch pigweeds you missed.

Another reason they should have be sprayed before they reached 2 inches is that at that size they begin to grow 2 to 3 inches per day. A farmer told me his scout told him on a Friday he had 2-inch pigweeds and they needed to spray Monday. In reality they should have been sprayed the Wednesday before.

When it is dry like it is in most areas now, every day brings with it more drought stress. As a result, the weeds not only getting larger each day you are late, and that combined with increasing stress results in a double whammy.

One thing I constantly hear from consultants is “my farmers are too big and too busy to get out a pre-emergence herbicide on their soybeans or to make timely applications.” I do not know the answer to that on any individual farm, but if you cannot resolve that issue, the pigweeds will do it for you. The pigweeds don’t care how busy any of us are.


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A lot of growers use custom application to take that load off them. I am glad we have custom applicators, but we do not have nearly enough of them. Everything happens for everyone at the same time. The pigweeds do not care if your field is “on the books or has been on the books for a week.” I believe most farmers are going to have to be set up to do at least some of their own spraying to be timely.

I thought soybean scouting would be easy and so did a lot of consultants. Boy, were we ever wrong. A lot of them have found it extremely frustrating and that is fodder for another article.

               You might also read:

Producers harness cover crops to suppress weeds

Metribuzin for pigweed in soybeans - fresh look


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