Burke – Jenkins Ag News

Prostko/Culpepper Weed Update

The following is some timely information from Dr. Eric Prostko and Dr. Stanley Culpepper. It is hard to believe that it is time to get our weed management plan into action. The herbicide activity relative to time of day is very interesting.

 

 

Halex GT + Atrazine Tank-Mixtures (Prostko)

It has recently come to my attention that there might be some problems when tank-mixing atrazine with Halex GT for postemergence weed control in RR field corn.  Halex GT, from Syngenta, is a 3-way pre-mixture of glyphosate + mesotrione (Callisto) + s-metolachlor (Dual Magnum).  Please refer to the information listed below to help avoid problems with this tank-mix

 

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Sicklepod/Cadre Resistance Update (Prostko)

Just wanted to let you know that my MS/PhD graduate student (O. Wen Carter), Dr. Ted Webster-USDA/ARS, and I recently completed our first round of greenhouse experiments investigating potential Cadre resistance in sicklepod. Since collecting the seed last fall, we have been able to test 8 populations (Figure 1). We are very happy to report that NONE of these 8 populations appear to be resistant!!!!! (Figure 2). We have 21 more populations to screen but will not likely tackle these until this fall (too busy in the field right now and greenhouse will be getting too hot).

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Figure 1. First 8 sicklepod populations tested for resistance to Cadre in Georgia. None were resistant!

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Figure 2. Susceptible AZ1 population (L) and suspect Georgia population DC4 (R) response to Cadre @ 4 oz/A + COC @ 1% v/v – 21 DAT. Both sicklepod populations had 93% fresh weight biomass reductions after the Cadre application.

 

 

Time of Day Impact on Herbicides (Culpepper)

Over the past few years, we have been studying the impact of application time of day on the postemergence activity of numerous herbicides. The table below is provided to help guide you in assisting your growers with timely applications. Liberty remains, by far, the most sensitive herbicide to the time of day in which it is applied. However, research is showing most herbicides applied early, late, or early and late may not perform at their optimum.

Consistent results from numerous locations have been generated with Liberty, Roundup, Clarity, and 2,4-D. For Reflex, Direx, and Gramoxone results provided are from a single location and the study will be repeated during 2015. Data results used to generate this table will be discussed in depth during the cotton section at Winter School on April 1, 2015.

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