All posts by Larry Steckel, Extension Weed Specialist

Concerns About Poor Palmer Amaranth Control with Dicamba

Palmer Amaranth Escaping 2 Applications of Engenia + Roundup PM. Crockett County TN. Pic taken 14 Days after 2nd Application

Calls continue to come in on concerns about poor Palmer amaranth control after a dicamba application. More than a few have reported that Palmer amaranth has survived multiple dicamba + glyphosate applications (Example above). Continue reading


UT Weed Tour Cancelled

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Dear Colleagues

The University of Tennessee Weed Tour has been cancelled.  Due to the covid-19 virus no large groups are allowed to visit a University research station.  Since we cannot have an in-person tour, we plan to post some short videos on the UT Crops News Blog highlighting some of the more interesting research from this summer.

Thanks,

Larry Steckel


Corn Maturity Cutoffs for Herbicides

Due to little time and very few good spray days some corn fields have yet to have their lay-by application. Corn is putting on a new leaf every 3 days with all the heat and water. Therefore time is short before it will be too mature to apply any herbicide safely over the top.

The most asked question “is how large can corn be before glyphosate could potentially cause injury”? The glyphosate label states it can be applied up through the V8 corn growth stage. My experience has been if glyphosate is applied to corn larger than that it can at times cause ears to be barren.  This phenomena is difficult to predict ahead of time as it can vary due to maturity of the corn at application, hybrid and weather. Continue reading


Palmer Amaranth Control with all the Uncertainty Around Dicamba

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As most know by now, on June 3rd the U.S. Court of Appeals for the 9th Circuit vacated the labels for XtendiMax, FeXapan and Engenia.  The question since is how do we proceed from here controlling weeds in Xtend cotton and soybean?

The folks at the Tennessee Department of Agriculture (TDA) have stated that until they get direction from the Environmental Protection Agency to the contrary, growers can still apply those herbicides according to the label directions. How long this will be is uncertain. It could be just a day, several weeks or depending upon legal maneuvers, well into July. Continue reading


Options to Manage Glyphosate-Resistant Johsongrass in Corn

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Johnsongrass escaping glyphosate + mesotrione: 14 DAA

Glyphosate is no longer an effective Johnsongrass herbicide in Shelby and Tipton counties. This problem appears to have spread, as field observations as well as follow-up research over the past 2 years would indicate that glyphosate is no longer effective on Johnsongrass in a few fields in Crockett, Fayette, Madison, Haywood and Lauderdale counties. Only the counties near the Kentucky line seem to be getting adequate control of Johnsongrass with glyphosate in most every field. Continue reading


Suggestions to Minimize Cotton Injury with First POST Applications

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This week will be the start of the early POST applications in cotton. These applications are often critical to not only curtail weed competition but to combat thrips injury as well. The biggest concern with these applications is injury to the young cotton plants. Continue reading