Recent Updates

Tarnished Plant Bugs Moving into Squaring Cotton

I’ve received a few calls on adult tarnished plant bug migration into squaring cotton. Silking corn, blooming soybeans and flowering weeds 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 around 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.


Avoid Inversions

Light fog bank over corn

Numerous observations on off-target herbicide issues often pointed to temperature inversions as a source for the problem. This occurs in one of two ways.  First when herbicide applications occur in a light fog bank that are generated by temperature inversions. These can be avoided by being vigilant and shutting down application during an inversion. The second way is when a volatile formulation of a herbicide like 2,4-D or dicamba pick up as a gas hours after application and join low lying fog which are generated by an inversion. These can be avoided by only using labeled low volatile formulations of 2,4-D as there is no label for dicamba in our row crops.  This means that dicamba cannot be legally sprayed in row crops. Continue reading


Herbicide Stewardship Crunch Time

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The weather forecast, if accurate, suggests next week will dry up enough where we all can get back in the field.  Everyone will need to be running sprayers as weeds have not stopped growing.  I know everyone will be in a rush, but please, please take the time to be good stewards and apply herbicides as directed by the labels. Continue reading


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 15th, 9:00 AM – 11:30 AM. This school will be held 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. Contact Sebe Brown for more information. 318-498-1283, sbrow175@utk.edu.

Middle TN Soybean Scout School
Middle TN Soybean Scout School

Middle TN – Robertson County, July 17th, 9:00 AM – 12:00 PM. This school will be held at 5233 Belt Rd, Springfield, TN 37172.  Contact Timmy Mann for more information. 615-384-7936, tmann1@utk.edu.

East TN – Monroe County, July 16th, 12:00 PM to 3:00 PM.  This school will be held at 501 Main Street, Madisonville, TN 37354. Contact Jonathan Rhea for more information. 423-442-2433, jrhea@utk.edu.


Weed Tour Next Wednesday

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JACKSON, Tenn. – The University of Tennessee Institute of Agriculture will host the annual Weed Tour June 18 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


Corn Herbicide Cut-off Stages

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4 – Leaf Corn

Due to little time and very few good spray days, some corn fields have yet to have their layby 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 many herbicides safely over the top. Continue reading