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Managing Early Season Plant Bigs In Cotton

• By Scott Stewart •

tarnished plant bug

Adult tarnished plant bug — photo courtesy University of Tennessee

Good early-season management of tarnished plant bugs relies on a sweep net, monitoring square retention, and making timely insecticide applications as needed. During the first two weeks of squaring, the recommended treatment threshold is an average of eight or more plant bugs per 100 sweeps.

After that, treatment is recommended anytime of infestations average 15 or more plant bugs per 100 sweeps (although we typically recommend using a drop cloth once blooming begin).

You should be more aggressive than the above thresholds if square retention is low (< 80-85%). Monitoring square retention is perhaps 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 an good indication that treatments are working.

I’m still comfortable using neonicotinoids by themselves during the first couple of weeks of squaring, including Centric, Belay or at a full-labeled rate imidacloprid. Some also use a reduced rate of Centric mixed with imidacloprid.

Although we have concerns about the decreasing performance of these products against nymphs, a quick look last year showed that they were still providing protection against early season adults. Centric or Belay is a better choice when facing high pressure.

Transform WG is an option, but I generally suggest saving that bullet until near or after first bloom. As we near bloom and expect to see more nymphs, either Transform (1.5 oz/acre) or a neonicotinoid that is tank-mixed with 4-6 oz/acre of Diamond are good choices.

My primary goal is for everyone to make at least one application of Diamond and/or Transform during the season. In my experience, these two products fit best in the window beginning about a week before flowering and the first two weeks of bloom.

I’m trying to limit the use of acephate before bloom (and Bidrin is not labeled for use between first square and first bloom).

This is partly to help preserve beneficial insects and also for resistance management as Acephate and Bidrin will typically be used extensively during mid- and late bloom.

There are a limited number of insecticides that can be tankmixed with Engenia or XtendiMax , and neither list includes Centric, Transform or Diamond. Several versions of acephate are available for both Engenia and XtendiMax, and one or more imidacloprid products are also listed.

There are premixed products listed that include imidacloprid (mixed with bifenthrin). However, I would discourage the use of these products prior to bloom in cotton.

The pyrethroid component (bifenthrin) of these premixes is generally unneeded, will have little efficacy on plant bugs, and can cause unnecessary problems such as the flaring of secondary pests. Plus, you are just paying for a component you don’t need.

The list of approved tank-mix partners is updated as new pesticides are added:

Engenia approved tankmix partners:

XtendiMax approved tankmix partners:

Dr. Scott Stewart is a University of Tennessee Integrated Pest Management Extension Specialist. He may be reached at sstewar4@tennessee.edu.