Recent Updates

Grass Weed Management Escapes

Infestation of goosegrass in cotton 2024

Serious infestations of goosegrass, junglerice and barnyardgrass have proven to be way too persistent in many cotton and soybean fields (Picture 1).  Many are getting frustrated with the lack of control seen with tankmixes that contain glyphosate and/or clethodim or quizalofop.  Some have asked if maybe some of these grasses have developed resistance to glyphosate, clethodim and quizalofop. Continue reading

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2024 UT Soybean Scout Schools

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 15th, 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.

2024 Franklin County Soybean Scout School
2024 Franklin County Soybean Scout School

Middle TN – Franklin County, July 16th, 9:00 AM – 12:00 PM. This school will be at 601 Cumberland St., Cowan TN 37318. Contact Matthew Deist for more information. 931-967-2741, mdeist@utk.edu. Register online at https://tiny.utk.edu/SoybeanScoutSchool

West TN–  Obion County, July 17th, 9:00 AM – 11:30 AM. This school will be held at the Obion Farmers Coop,  810 Mt. Zion Rd Union City, TN 38261. Contact Garrett McDaniel for more information gartmcda@utk.edu, 731-223-1178.

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Tarnished Plant Bugs Migrating into Squaring Cotton

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I’ve received a few calls on adult tarnished plant bug migration into squaring cotton. Silking corn, blooming soybeans and flowering pigweed all contribute to large increases in plant bug numbers that make their way to ThryvOn and non-ThryvOn cotton.  ThryvOn’s bt gene can help reduce the amount of injury plant bugs inflict to squaring cotton but adults, especially large numbers of adults, can knock squares off of ThryvOn just like non-ThryvOn. I’ve seen ThryvOn cotton go from 90 plus percent square retention to sub 50 percent in 5 days due a large, consistent migration of adult plant bugs. The biggest benefit we see from ThryvOn is the reduction of plant bug immatures in bloom. That being said, you will typically see increased square retention in ThryvOn vs non-ThryvOn throughout the fruiting period. Scout your cotton and don’t ignore migrating plant bugs in ThryvOn or non-ThryvOn.  Also, many of the newer varieties begin squaring on the 5th or 6th node and we need to quickly transition from scouting for thrips to plant bugs.

TPB Adult
TPB Adult

Based on field reports, 2.0 oz/a of Centric is performing well on plant bug populations. Although the same class of chemistry, imidacloprid’s performance is fair at best and recolonization often happens quickly after an imidacloprid application. I try to not recommend consecutive applications of neonics due to efficacy falling off after the first shot. However, consecutive shots of neonics may be warranted for several reasons (cost, presence of mites, personal choice etc.) and on the second application I tend to increase rates of Centric to 2.5 oz/a especially if it was used previously. After the second application we’ve pretty much exhausted that chemistry. Other options are: acephate which carries a high risk of flaring mites and aphids especially in our current dry period, Vydate which is effective in killing plant bugs but has limited residual, roughly 36 hours, Bidrin isn’t labelled for plant bugs between first square and bloom, Transform, which is very effective, but is expensive and many want to save those shots for bloom unless aphids are present and Diamond. Diamond’s activity is best utilized in the 3rd week of squaring to first bloom window, several studies at MSU and UT have shown the best ROI of 6.0 fl oz/a Diamond during that time period.

Final note, I’ve received a few questions on squaring cotton having poor square retention but very few or no plant bugs are found scouting. Adult plant bugs, especially at this time of year, will move in and out of cotton quickly. The abundance of alternative hosts facilitates movement in and out of cotton without colonization. The take home is since most are scouting once a week, it is prudent to be more aggressive with applications and not risk square retention falling below 80% if you’re close. Monitoring square retention is one of, if not, the best way to determine if early-season treatments are working. Migrating adults can give the impression of an insecticide failure, but maintaining good square retention is a good indication that treatments are working.

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Weed Tour This Thursday June 20

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JACKSON, Tenn. – The University of Tennessee Institute of Agriculture will host the annual Weed Tour this Thursday, June 20 at the West Tennessee AgResearch and Education Center. The guided tour will feature 60 weed management research tests in cotton, corn and soybean.

Weed Tour runs from 9 – 11:30 a.m., with registration opening at 8:30 a.m. Continue reading

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Late Burndown in Soybean

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Picture 1. 3 foot tall goosegrass, fall panicum and Palmer amaranth that need to be burndown before soybean planting

The question of the week is on how to burndown fields that are grown up messes before planting soybeans (Picture 1).  The problem is when fields are heavily infested with 3’ tall goosegrass, Palmer amaranth, horseweed and volunteer corn that is tasseling there are no good answers. Continue reading

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Nitrogen loss potential in wet corn fields

From late April and throughout the month of May, many parts of Middle and West TN have received persistent rainfall that is well above the average for this period. These rains have produced persistently wet soil conditions and have coincided with sidedress N fertilizer application where most or all of the recommended N is applied. With this much rain, there is potential for N loss. Continue reading

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