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Weed control in conventional soybeans

I’ve enjoyed getting more involved in soybean weed control again. For years I did more soybean work than anything else. The work Dick Oliver and I did on reduced rate herbicide programs years ago was one of the most rewarding things I have done professionally. Being in on the ground floor of evaluating the Roundup Ready technology and having a part in developing the weed control recommendations for Arkansas was probably the most fun I ever had as a weed scientist.

I am on record many times as saying Roundup Ready is miracle technology. However, ever since it received widespread grower acceptance, there has not much demand for an applied weed scientist in soybeans — until now.

The increase in glyphosate-resistant weeds and the development of new weed control technology in soybeans has put weed scientists back in demand in that crop.

This year, I have had an increasing number of questions about weed control in conventional soybeans. Like my comments on soil residual herbicides, I am supportive of planting more conventional soybeans — where they have a fit.

Several articles have been written recently about conventional soybeans, and it has been pointed out that there likely is not enough seed to make a big splash. However, there is some seed out there, and some variety development work is being done. If demand for them increases, my guess is the companies will respond and more seed will become available.

My interest, however, is weed control, so a brief review of weed control in conventional soybeans might be in order. Perhaps the best opening statement I can make about weed control in conventional soybeans is if it had been easy and if things had been going well with weed control in the early 1990s, Roundup Ready would not have taken essentially 100 percent of the market by storm.

That may sound like a very negative statement, but stay with me. I do not mean to be negative. Soybean farmers who have only been in the business 10 to 15 years missed out on the weed control challenges in conventional soybeans. I am all for you, but spraying glyphosate is all you have known.

The guys who were farming before Roundup Ready may remember weed control in conventional soybeans, but it has been so easy for so many years, you, too, may have forgotten how challenging it could be.

I will first discuss why weed control in conventional soybeans can be so much more challenging and then point out where they can have a nice fit. One of the main problems controlling weeds in conventional soybeans is in most fields you are trying to control a broad spectrum weed problem with narrow spectrum herbicides. That means making multiple herbicide applications and most of the herbicides are not nearly as forgiving as glyphosate has been.

I will write more on this in the next article, and will end this one by saying there is a place for some conventional soybeans. Conventional soybeans are much better suited to the cleaner fields and fields where some of the more difficult-to-control weeds such as sicklepod and Palmer pigweed are not a problem.

One would think that as long as Roundup Ready soybeans have been available and also where these have been rotated with rice or corn there should be a lot of clean-field candidates. However, I have also noted a lot of weed control slippage in Roundup Ready fields the past couple of years.

Keep in mind also that conventional weed programs require a much higher level of management. This does not mean I think there are a lot of poor managers out there. However, guys who have primarily known soybean weed control to be a couple of shots of glyphosate over the top can be in for a big surprise. I will start here next week.


TAGS: Soybeans
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