Field Management Techniques to Combat Resistant Weeds

On Thursday, Bayer CropScience hosted a “Respect the Rotation” event near Mt Olive, North Carolina. The purpose is to teach producers how to rotate crops, as well as modes of action on herbicides, as well as using other methods to combat glyphosate resistant weeds, primarily Palmer pigweed. NC State’s Dr. Allen York spoke at the event about other field management techniques:

“There is no question that if I’m in conventional tillage and I’m stirring the ground vs no tilling and I’m not stirring it up, I’m going to have more come up in a conventional tillage. If you have a cover crop out there you are going to get suppression of the pigweed coming up. The catch is, pigweed is such a tremendous weed that a little bit of cover crop wont cut it.”

Dr. Stanley Culpepper at University of Georgia’s Tifton Research Station has done quite a bit of research involving winter rye as a cover crop, according to York:

“They put out a good seeding rate of at least a bushel of rye and let it get a good head high before its killed and rolled. Otherwise you cant see where you are or do any planting. You roll it in the same operation as you are planting.”

When York says “roll” he doesn’t mean round bale, he means literally flattening the desiccated rye onto the ground, then planting into the mat on the field:

“You will need a row cleaner in there to get the seed into the ground so there may be some weeds that come up in that strip. But if you’ve had head high rye and done a good job rolling it flat, you will have about a four inch mat and as good as the pig weed is, it wont be able to get up all the way through that.”

This particular method of pigweed control has the added benefit of moisture conservation, according to York:

“There are moisture retention benefits, but from a liability standpoint, if you wait too long to desiccate it, you will have that green crop growing and taking all of the water out of the ground. But if you kill it a bit ahead of planting it wont be taking up any more of the moisture. And now you have that cover on the ground it really cuts back on the evapo-transpiration rate.”

Some other research out of Tifton, Georgia involves bottom plowing:

“They have looked at no till bare ground and no till cover compared with the bottom plow. They have found that the bottom plow is cutting the emergence of palmer by about half. But keeping in mind they are not bottom plowing every year.”

NC State’s Dr. Allen York


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