Tuesday, July 26, 2011

Our Summer Weather Perfect for Cotton ... and Pests

Cotton plant develops first bloom.
You can’t ask for better cotton growing weather.

Our recent daytime temperatures in the Valley have been hovering around the low 90s. Plants are doing well and are in their second position square on the seventh node.

Conditions are perfect – for pests, too.

As growers head into the final critical three weeks for the cotton crop to set this season, I’m seeing increased pressure from lygus and worms. They are migrating from nearby safflower, which are now drying, and from neighboring harvested alfalfa fields. Growers can treat their safflower for lygus as well as leave uncut strips of alfalfa to keep these pests from moving into cotton.

Lygus a threat to cotton.
- Jack Kelly Clark photo
As I scout the cotton fields, I’m collecting in my sweep net as many as 11 adult lygus and nine to 10 lygus nymphs (which feed on the cotton squares). I can’t stress enough the importance of sweeping your fields twice a week so that you can the upper hand on any potential square losses. Check the University of California Statewide Integrated Pest Management online site for more information about lygus and cotton and for treatment thresholds.

When treating your fields, it’s important to select softer products that won’t harm beneficial insects such as green lacewings, big-eyed bugs and ladybugs. Belay and Carbine of some of the good products on the market.

Without natural predators around, you may be opening a Pandora’s box for an outbreak of crop-damaging pests such as aphids. In the end, you could wind up making a second or third pest control application to take care of these problems. That's money you can spend on something else.

Speaking of beneficial bugs, I’m releasing about 5,000 to 10,000 green lacewing eggs per cotton field to help control aphids. A single lacewing larvae can gobble up about 90 aphids a day. Put up the "Hard At Work" sign for these tiny natural pest control workers. 

Here I'm releasing green lacewing eggs in rice hulls on young cotton plants. 

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