Category Archives: Weeds

2022 UT Soybean Scout Schools

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UT’s Soybean Scout Schools will be held in July (see details below). These field-side programs cover the basics of soybean growth, scouting, pest identification, and general management. Pesticide recertification and CCA CEU points will be available. Scout Schools are offered free of charge with sponsorship from the Tennessee Soybean Promotion Board. Registration is not required. Participants will receive a scouting notebook and a sweep net while supplies last.

West TN – Madison County, July 11th, 9:00 AM – 11:30 AM. This school will be at the West TN Research and Education Center, 605 Airways Blvd. Jackson TN, 38301. Signs will be up at the station to direct you to the field.

West TN – Henry County, July 12th, 9:00 AM – 11:30 AM. This school will be at Norwood Farms, 645 Norwood Rd, Mansfield, TN.

Middle TN –  Lincoln County, July 13th, 9:30 AM – Noon. This school will be at H&R Agri-Power, 11 Highland Rim Road, Fayetteville, TN 37334.  Lunch will be provided courtesy of H&R Agri-Power. A head count is required for the meal,  please contact Bruce Steelman of the UT Lincoln County Extension Office at (office) 931-433-1582 or (cell) 615-542-1364 if you plan to attend.

 


Junglerice and Barnyardgrass Management in Soybean and Cotton

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There have been several reports last week of multiple glyphosate and/or clethodim applications not controlling barnyardgrass or junglerice.  We really do not know the precise reasons for the lack of control in any given field but based on previous research and past experience there are a couple likely causes. Continue reading


Managing Palmer Amaranth

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(Picture 1) Pre applied herbicide breaking earlier than in 2021

Judging by our research plots as well as walking some cotton and soybean fields most Pre applied herbicides are playing out about 7 to 10 days quicker than last spring (Picture 1).  The frequent rain would most likely be the reason for this. Continue reading


UT Weed Tour (June 15, 2022)

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JACKSON, Tenn. – The University of Tennessee Institute of Agriculture will host the annual Weed Tour next Wednesday, June 15 at the West Tennessee AgResearch and Education Center. The guided tour will feature 60 weed management research tests in corn, soybean and cotton as well as a demonstration of herbicide symptomology. Continue reading


Best Management Practices for Liberty Applications

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The beginning of June is always a busy planting and spray window.  It will be more so this spring with most of last week a wash to get much field work done. Of course, there will be a good deal of glyphosate and dicamba sprayed this week and likely some Liberty as well. With Liberty in such short supply every quart must count.  This is just a quick reminder that the time of day that Liberty is applied has a large determination on the success or failure of that application.

From 2012 to 2017 we conducted a good many studies examining Liberty performance on Palmer amaranth as affected by the time of day the application was conducted.  All the studies pointed to the same conclusion, that Liberty applied in the middle of the day provided better and more consistent control of Palmer amaranth than either early morning or evening applications (studies conducted in warm weather). As an example, one study (Figure 1.) from 2015 showed good control of 4” tall Palmer amaranth if the Liberty application was applied at noon compared to applications made at dawn or sunset.

Figure 1. Palmer amaranth control from Liberty herbicide as effected by application timing.

In general, the best Liberty performance can be achieved when applications are made from 8:00AM to 6:00PM.

Other environmental factors also greatly effect Liberty’s weed control performance.  It controls weeds best if applied on days where the high temperatures for the day are in the 80s or 90s.  Also, it works best at higher humidity’s as well.  In other words, a typical June or July day.


UT Cotton Scout School

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The UT Cotton Scout School is scheduled for the last Friday of the month, May 27th, at the West Tennessee Research and Education Center (605 Airways Blvd, Jackson). There is no fee, and preregistration is not required. Registration begins at 8:00 AM with the program starting at 8:30. Content will include classroom and hands-on training with an optional go-to-the-field session after lunch. Topics covered will include cotton development and identification and symptoms of insect pests, plant diseases, and weeds.


Seedling Cotton Burn from Early Post Applications

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Picture 1. Cotton growing through Dual Magnum + Roundup PowerMax Burn

Weather permitting, 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.  Traditionally, the main pesticides applied are a mixture of glyphosate plus either Dual, Outlook or Warrant plus Intrepid Edge or acephate. Those herbicides which contain a good surfactant in glyphosate with the oil formulations of the chloracetamide herbicides will always burn young cotton leaves. The typical cotton injury from those mixtures will range from 10 to 20% (Picture 1). Continue reading


Ryegrass and Johnsongrass: Where do we go from here?

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Picture 1. Ryegrass infestation in wheat escaping Osprey
Ryegrass in corn escapes glyphosate + dicamba burndown

Ryegrass has moved from being an aggravation 10 years ago to a significant weed issue in our row crops.  In wheat at this point, the yield loss caused by the weed has occurred (Picture 1). In cotton and soybeans, clethodim can be used now to push this weed on to maturity. In corn, there is no real solution to controlling it other than spraying the typical POST corn premix and hoping that pushes the ryegrass on to maturity (Picture 2).

The wheat fields that were consistently clean of ryegrass were those treated with either Anthem Maxx, Zidua or Axiom last fall.  A good bit of the ryegrass population in the state is resistant to ALS-inhibiting herbicides which renders herbicides like Osprey, Finesse, and Powerflex harmless to ryegrass. Axial Bold has shown improved ryegrass control in spring applications over those ALS-inhibiting herbicides but it does not offer the consistent ryegrass control as those delayed PRE-applications of Anthem Maxx, Zidua or Axiom.

Johnsongrass is also a consistent problem in a good many cornfields. Glyphosate is just not providing any traction in the burndown on Johnsongrass and the POST in-crop applications are no better.  Our most recent research funded by the Tennessee Corn Checkoff program has shown that Steadfast Q or Accent Q can still provide good control of Johnsongrass when glyphosate fails.