Aphid and Whitefly Infestations Lead to Sticky Problems

It’s a safe bet you’ll find lots of folks enjoying some sticky cotton candy at next month’s Big Fresno Fair. Valley cotton growers certainly hope that’s the only place you’ll find any kind of sticky cotton.

With the last irrigation complete, we’re now at cut-out – the last stage of cotton plant development before the bolls start to open. Our attention focuses on cracked bolls and insects, especially aphids and whiteflies.

Sticky cotton impacts the fiber quality.

In late summer and fall, aphids and whiteflies are the major pests in cotton. This season, I’m seeing more whiteflies than normal in the fields. These pests secrete sugary honeydew on the cotton plant, which can contaminate an open boll. A sooty mold growth on the fiber creates sticky cotton.

The late-season insects can cause damage in the lint as it goes through the gin as sticky cotton. Sticky cotton affects the quality of the fiber and results in a markdown in grade, costing growers money in the long run.

Whiteflies found under the leaf.

To prevent an infestation, you need to monitor their fields for these pests. Divide your field into four different parts. Pull 20 to 25 leaves from each section, giving you a total of 80 to 100 leaves for the entire field. Then inspect the back of each leaf for aphids and whiteflies.

Check the University of California Statewide Integrated Pest Management website for monitoring guidelines and treatment thresholds for aphids and whiteflies in cotton.

Monitor plants for aphid problems.
- UC IPM photo

If you need to treat for these pests, remember to ask your PCA about softer materials that won’t harm beneficial insects. Using stronger materials could open up a Pandora’s Box to other problems in the future.

Right now, mites and worms aren’t a major concern. Still growers need to keep an eye out for potential problems with worms that can damage young bolls.

Have any questions about pests and the upcoming harvest? Get your answers at our Cotton Production and Pest Management Field Day on Wednesday. It will be from 10 to 11:30 a.m. at the McCurdy Farm, south of Firebaugh. UC Cooperative Extension cotton specialist Dan Munk will provide lots of valuable tips about timely cotton termination and more advice about avoiding sticky cotton. I will be there to give a field scouting update. Check our Sustainable Cotton Project website for directions. You also can earn 1.5 hours of continuing education credits. See you there.