LITTLE ROCK, Ark. — A week or so of relatively high winds across Arkansas delayed a much-needed application of herbicides to the state’s soybean crop, said Chris Tingle, soybean specialist with the University of Arkansas Cooperative Extension Service.
“Overall, the crop looks really good. It’s just extremely weedy.” He said a rainy spring has caused excessive weed growth. “I’m seeing a lot of morningglory weeds, barnyard grass and pigweed,” Tingle said.
“Our herbicides, when applied at the right time and right rates, will control them without problem. But when we see a delay in making applications, like we’re experiencing now with the winds, we may have a lack of control over these weeds when farmers are finally able to spray. The weeds are getting bigger the longer we wait.”
Tingle said soybean farmers in the past typically used pre-emergence herbicides to control weeds before they could emerge. Now, about 85 percent of the state’s soybean crop is Roundup Ready. Farmers can spray Roundup or glyphosate after weed emergence and get good weed control relatively inexpensively.
But winds are making aerial and ground applications of this herbicide difficult. Tingle cautioned farmers to use care to minimize the chance of glyphosate drifting onto neighboring crops. Rice and corn are sensitive to the herbicide.
“When you have 20 mile-an-hour winds gusting up to 30, you’d better be careful. Growers can’t be sure where droplets are going to land. Much of our beans are planted up against rice, and rice is in a sensitive stage. Low drift rates of Roundup may not kill the rice, but it can damage plants and potentially decrease yields.”
Tingle has heard of a few drift problems. He hopes most farmers will wait for better weather. “If farmers tried to spray this week, I expect to hear about problems. If this wind ever dies down, you’ll be able to smell glyphosate in the air.”
Meanwhile, Tingle said farmers and county agents are telling him that they need rain. The wind and warmer temperatures have helped farmers still planting crops, but the conditions are rapidly drying out the ground for some farmers with soybeans that have emerged.
Tingle said early-season soybean varieties are off to a good start. He said many fields have already received herbicide applications. Both glyphosate and conventional herbicides appear to be doing a good job of controlling weeds. Second applications will be applied when the wind permits.
Many of the full-season fields were planted in the third week of May, and the remainder were expected to be planted by the end of May. Some double-crop fields were to be planted in the last week of May in southeast Arkansas, the Extension specialist said.
Tingle’s regularly updated Soybean Notes can be read at http://www.aragriculture.org/News/soybean_notes/default.asp
Lamar James is an Extension communications specialist with the University of Arkansas.