All posts by Larry Steckel, Extension Weed Specialist

Options to Manage Glyphosate-Resistant Johsongrass in Corn

 

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


Management of Grass Escapes from Paraquat Burndown

Junglerice recovering from paraquat burndown

Recent burndowns that are targeting Palmer amaranth with paraquat are working quite well on that weed.  Unfortunately, that is not the case on some grass weeds like barnyardgrass, junglerice and crabgrass.  Once those grasses get 4” or more in height paraquat often struggles to provide good control. Continue reading


Dicamba Application Best Managment Practices

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Wet and cold with more rain in the forecast. Ugg! That sums up our spring planting season to date. Hopefully, next week, we will get our break and can get a good bit done in the field. When that time comes, please remember to use best management practices applying all herbicides but particularly dicamba containing products! Continue reading


Results of UT Studies on Reasons for Junglerice Becoming a Major Pest in Tennessee Xtend Cotton and Soybean Acres

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Junglerice Escaping: Glyphosate+Engenia /fb Glyphosate+Engenia+Clethodim

The results of some studies UT Extension has done to try to determine why junglerice has become a major weed pest in Tennessee Xtend cotton and soybean acres has provided some insights. This research was in-part supported by the Tennessee Soybean Promotion Board and from Cotton Incorporated. Continue reading


Destroying a Poor Stand of Corn and Replanting Back to Corn

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Judging from recent conversations there will be a significant number of corn acres that will need to be replanted.  The long cold and wet spell apparently has greatly hindered getting a good stand in some corn fields. Fortunately, there are several options to control a thin corn stand and replant back to corn.

The options, like Select Max, need a waiting period before it can be planted back to corn.  Others, like tankmixes of paraquat plus atrazine, allow corn to be replanted right away.  Please find attached the results of a study Angela McClure and I conducted on destroying freeze damaged corn and replanting back to corn. We repeated the study the following year on a good stand of corn and got similar results. In this publication (Replanting corn in a failed corn stand) you will find a number of different herbicide options that did a good job controlling an unwanted stand of corn.

Many over the past decade have used the recommendations to satisfactory results.  The most consistent time to control an old corn stand is around the V2 corn growth stage, which was the timing the research was conducted.  Our experience has been over the years that once the old corn stand matures past V2, results from the herbicides in the publication will likely be more sketchy.  In those cases, consider using higher rates of the herbicides in the publication to improve the chance for good control.

 


Poa and Ryegrass Causing Burndown Issues

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Poor control of poa (annual bluegrass) and ryegrass have been the common calls of late.  This is becoming more common every spring.  It would appear that an increasing portion of the poa and ryegrass populations in Tennessee has evolved some level (2 to 4x) of glyphosate resistance.

Poa Escaping Roundup PM + Sterling Blue 14 DAA

Continue reading