Plant bug numbers are increasing across the landscape, and squaring applications are right around the corner. Silking corn, blooming soybeans, and flowering weeds all contribute to large increases in plant bug populations that eventually move into both ThryvOn and non-ThryvOn cotton. Continue reading →

ThryvOn: ThryvOn is Bayer’s Bt technology that has activity on thrips and plant bugs. ThryvOn cotton varieties are very effective against thrips and it is not anticipated that any fields will need foliar  treatments. ThryvOn will still have thrips present (adults and immatures) but insecticide applications should not be triggered on thrips numbers but damage level (Fig 1.). Applications should be initiated when plant damage is approaching 3 in figure 1. That being said, I’ve evaluated ThryvOn varieties for several years under excellent and terrible growing conditions and I as well as my colleagues across the cotton belt, have never recommended a foliar spray for thrips.

In-furrow: In-furrow liquid applications of imidacloprid are more effective than seed treatments; however, resistance development to neonicotinoids are diminishing the efficacy of imidacloprid in-furrow. Fields with in-furrow imidacloprid may still require a foliar spray under heavy thrips pressure. Granular AgLogic (aldicarb 15G) is highly effective against thrips populations and works like aldicarb should.

Insecticide Seed Treatments (ISTs): ISTs are the predominate control method for thrips in cotton. IST performance can be highly variable depending on weather conditions and thrips pressure. High thrips pressure and poor growing conditions will often necessitate the use of foliar sprays even with ISTs. Seed treatment packages typically come in a base (storage rate of imidacloprid + fungicide) and field rates of imidacloprid (these have several names) + fungicides, others may have nematicides, biologicals etc. Base treated seed may as well have no insecticide, the small stored product rate will offer almost no control of insects in the field. Standard options of imidacloprid (0.375 mg ai/seed) are the minimum needed for insect control in field cotton.

Foliar Spray Options: My recommendations are going to be limited for foliar sprays. Based on ongoing tobacco thrips resistance monitoring, to organophosphates (OPs), started by Scott Stewart several years ago, I am hesitant to recommend Orthene or Bidrin for thrips sprays. Resistance levels, in assayed populations from West TN, and the number of complaint calls I received last year are a good indication that OPs have limited use against our tobacco thrips populations. There may be areas where OP’s worked last year but it’s hard to say if they will work this year. That being said, Intrepid Edge at 3.0 fl oz/a is my go to for foliar thrips control. Although more expensive than the OPs, Intrepid Edge runs no risk of flaring mites or aphids and a surfactant has shown to increase efficacy (herbicide surfactants will work if you’re co-applying). Recolonization vs failure is another subject with foliar sprays. Presence of adults doesn’t mean the application didn’t work, adult thrips are always present on seedling cotton. Presence of immature thrips means adults are feeding and laying eggs and whatever control method you used is broken.

The Two-spotted cotton leafhopper or cotton jassid, has been making its way across the Southeastern cotton production areas with confirmed catches in Florida, Georgia, Alabama and South Carolina. Cotton jassids are small, sap-sucking insects that feed on the underside of leaves, causing “hopperburn”—a rapid yellowing, reddening, and browning that can quickly weaken plants. Native to Asia and first reported in Puerto Rico in 2023, this pest was confirmed in Florida in 2024 and has NOT been found in Tennessee fields in 2025.  insecticide efficacy trials are underway, in affected states, to determine what insecticides are most efficacious and what the jassid’s impacts are on cotton yields.

The threshold at which treatment is recommended for the cotton jassid is one to two nymphs per leaf. To scout, we recommend looking on the underside of the main stem leaf on the third, fourth, or fifth node from the top of the plant. Again, the threshold is one to two nymphs per leaf with injury present anywhere in the field. This helps to confirm the correct insect ID, as other leaf hoppers will not cause these symptoms. Populations and symptoms usually begin on field edges before moving into the field.

For the 2025 Tennessee crop, I’m not overly concerned with cotton jassids. The vast majority of our fields have reached the finish line and are awaiting defoliation. We don’t need to add another insecticide expense to a crop that has struggled to be profitable since it was planted. That being said, if you suspect jassids are in your cotton please reach out to your county agent.

The bollworm flight has been in decline in several areas. Our trap catches have returned to single digits in several counties. A general decline in plant bug populations is also being observed, but stink bugs continue to linger. Some fields of cotton have now reached a maturity where we should and have terminated insecticide applications for plant bugs, stink bugs and bollworms. For later maturing fields, it may still be necessary to manage pest infestations for a couple of more weeks.

Keep in mind that the average last effective bloom date is upon us (August 15-20^th). This is the average date that a white flower has a 50% chance of making a harvestable boll. It is a roll of the dice whether bolls set after this date have time to mature before a frost. For late maturing fields that are just now or have not reached NAWF5, it is still advisable to continue to good insect management practices for 2-3 weeks to allow these last bolls to accumulate enough heat units to be relatively safe from insect attack.

• Insecticide applications for plant bugs can be terminated when cotton has accumulated 250-300 DD60s past NAWF5 (NAWF5 = average of 5 nodes above a first position white flower).
• Insecticide applications for stink bugs can be terminated when cotton has accumulated 400-450 DD60s past NAWF5. However, fields free of stink bugs at 350 DD60s past NAWF5 are unlikely to develop economically damaging infestation after this point.

With the above considerations in mind, producers can potentially relax thresholds since we’ve reached the last effective bloom date.

1. The last effective bloom date mentioned above represent a 50% chance that a new boll will make it into the picker. Thus, there is a pretty good chance these bolls will not contribute to yield.
2. The upper, less mature bolls typically are smaller in size and number and represent a relatively small proportion of the overall yield. This assumes average or better boll retention on the bottom two-thirds of the plants.

My suggestion from this point forward is to pay better attention to stink bug and active bollworm infestations than to plant bugs. Stink bugs and bollworms are more likely to injure bolls. Spending a lot of money to protect squares and small bolls from plant bugs at this late date is a questionable decision. Of course, we have some built in protection from bollworm because almost everything is Bt Cotton. However, Bollgard 2 cotton in particular does not always provide adequate protection against moderate to heavy infestations, and insecticide applications may be justified. Bollgard 3 and Widestrike 3 cotton varieties have held up well this year, however; Bt expression can also decrease at cutout and beyond. Keep an eye on fruit damaged potentially damaged by bollworms out to NAWF5 + 400 DD60’s. Final clean up shots need to have a pyrethroid, OP or combination of the two to take care of stink bugs, plant bugs and potentially catch a stray worm in the top.