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Pitfalls of soil residual herbicides

This is another one of those articles I simply have to ask: “Why are we doing this to ourselves?”

I am now reading newsletters and hearing comments from weed scientists recommending growers plow up Roundup Ready cotton and soybean fields due to escaped resistant pigweeds and try to find LibertyLink seed. Why was the field not planted to LibertyLink the first time?

I am also getting phone calls from growers who want to burn down knee-high resistant pigweed and marestail with Ignite in order to plant Roundup Ready soybeans. When I ask, “Why don’t you plant LibertyLink soybeans so you have two more shots at weeds you are only going to burn back with the first application of Ignite,” I get a myriad of answers that all make me scratch my head.

I wrote the entire winter of 2005 that the light at the end of the tunnel with Roundup Ready crops was the oncoming train. I did not get many listeners. I have watched my university counterparts deliver an excellent message on herbicide resistance without a lot of results so far.

Unfortunately for me, I am one of the few weed scientists old enough to have a lot of experience trying to control Palmer pigweeds before Roundup Ready came along. I am on record many times over the past three or four years saying growers could not make conventional herbicide systems work consistently before Roundup Ready and they will not work consistently now.

Conventional herbicides are a necessary part of a resistance management program, but you can not over-depend on them where you already have a problem.

At least five or six things can happen with a soil residual herbicide program and at least four of them are bad. First, they can work perfectly, which is what we all hope for. More realistically they will provide partial control, which is a much more realistic expectation. However, you may fail to apply them, which happened a lot this year. You may apply them but get no rain for activation and they fail, which happened some this year. You may also get too much rain at the wrong time and get crop injury, which happened some this year. You may also get too much rain and get early control but have it play out too quickly, which happened a lot this year.

When you get partial control from the residual herbicide and then miss the timing of a Flexstar or Ultra Blazer application a few days (which happened a lot this year), it is all over but the shouting.

I am a firm believer that LibertyLink crops provide the best chance of surviving the resistant weed train wreck. I do not advocate them as a replacement for Roundup Ready crops but used in an integrated system with Roundup Ready and conventional crops and conventional herbicides.

LibertyLink crops need to be integrated into the system before the train wreck — not after the Roundup Ready crop has to be destroyed due to the resistant weed.

It is time for basic manufacturers and resellers to look at what is best for the farmer three to five years down the road as opposed to what may look best for the bottom line this particular year. If we are going to successfully manage our way out from in front of the train, it is going to be with a well-planned integrated approach with crops, herbicides and herbicide technologies on every acre starting now.

I see us headed down the same road with Clearfield rice that we are going with Roundup Ready crops. This year I am hearing more farmers say, “Apparently the only way I can keep Newpath off my conventional rice is to plant all Clearfield.” We are headed down the same road of getting 100 percent of our crop in the same technology. When it blows up, and it will, maybe LibertyLink rice or some other technology will come along to bail us out… maybe it won’t.

If I sound testy, it is because I am. I am watching us farm ourselves out of technology for the sake of tradition and convenience. If we change, it is going have to be from the grower level up.


TAGS: Soybean
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