Tarnished plant bug numbers seem to be all over the board in 2024. Some fields have one spray since square set and others have had upwards of five. Crop age and what’s neighboring your cotton play a large part of how intense plant bug pressure is over time. That being said, keeping an eye on square retention is the best gauge to determine how well your insecticides are performing. Most I’ve talked to have applied Diamond at least once since first bloom. Diamond shines when you catch early plant bug hatches often after large adult migrations during late squaring and we see a good ROI with Diamond around that 1^st week of bloom timing.

Going into bloom, I don’t think neonics have a fit in any scenario. Every time we test a neonic sprayed after bloom its often one of, if not, the worst treatments in the test. Once you see a flower migrate to the Transform, Acephate, Bidrin treatments. Pyrethroids can be added in with OP’s to help increase control and acephate + pyrethroid can catch a few bollworms in the top of the canopy if you’re close to cut out (although our 3 gene cottons are doing a great job of controlling bollworms). Diamond should rotated around in the bloom mix also. Overlapping Diamond residual, usually spaced out every other shot, can help reinforce control of nymphs. I don’t like Diamond fb Diamond in succession. Diamond’s effects may take 7 to even 10 days to notice and sequential shots may not take full advantage of the residual it provides, but that’s situation dependent.

Thryvon bloom performance is on par with what we’re accustomed to seeing. Square retention is often better in Thryvon and plant bug numbers, especially nymphs, are lower. Insecticides seem to perform better in Thryvon for a couple of reasons. Less insects are typically easier to control, plant bug population growth is slower and we think the nymphs don’t settle in bracts/blooms like they do in non-Thryvon. Nymphs are constantly moving in Thryvon and the more they move, the higher likelihood they’ll encounter an insecticide.  Final note, Thryvon has minimal, if any, activity on stink bugs and if you’ve gotten by without using a broad-spectrum insecticide mid to late bloom, I would add an OP or pyrethroid to clean up any building/lingering populations.

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 5^th or 6^th node and we need to quickly transition from scouting for thrips to plant bugs.

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 3^rd 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.