Protection from tarnished plant bugs

With cotton squaring, growers should have someone scouting their fields weekly for tarnished plant bugs.

With the dry conditions, most of the adults are in silking corn. As corn pollinates and the silks dry, I expect many of these adults to move into cotton, especially if dry weeds continue to be a poor host.

It pays more to protect cotton from tarnished plant bugs early (during squaring and early bloom) than later. By protecting the earliest squares, we can set fruit earlier and potentially make an earlier-maturing and higher-yielding crop.

This is a pest with a spatially spotty distribution. The only way to effectively manage tarnished plant bugs is to treat each field individually.

Even within a field there will be hot and cold spots for tarnished plant bugs. Check both high vigor (preferred area) and non-high vigor (non-preferred area) areas of the field.

How to scout and when to treat. Squaring cotton (pre-bloom) should be sampled using a standard sweep net. TPB are often unevenly distributed in cotton fields, scouting stops need to be spaced across the entire field if possible.

Keying in on local landscape features (e.g., corn) can identify hot spots in the field. Be sure to average across all sampling stops. Remember to switch to a drop cloth after the crop begins blooming.

Squaring cotton (pre-bloom) should be treated if square retention drops below 80% AND 8 TPB per 100 sweeps. There is no need to protect cotton from square loss above 80%, even with the delay this season. Once cotton blooms, switch to 2-3 TPB per drop cloth sample (5 feet of row).

What to treat with can be tricky. July is the time in the season when we need to preserve beneficial insects for bio residual. Select an insecticide that is safe on beneficials. Contact extension office for recommendations.

For more information on cotton production visit the NC State Cotton Portal Page. For all crop related questions contact Lance Grimes at (252)789-4370 or lance_grimes@ncsu.edu.