Sticky Cotton Watch Begins with the First Open Boll

 For cotton growers, now is the time for them to start seeing the fruits of their long, hard labor.

It’s when the thick greenish, cotton bolls start to crack open – like a chick cracking through an egg shell. What emerges is the long, cotton fiber or lint. This is a sure sign that cotton’s journey is taking another step forward toward the fall harvest.

Field scout Carlos Silva reports sightings of the first cotton bolls opening in some San Joaquin Valley fields. It won’t be long before others fields start resembling a carpet of white pop corn. “The plants are full of bolls. They’re ready to start opening up.”

Of course, there’s little time for growers to admire this transformation. There’s still a long time before the crop is hauled off to the gin. And there still are lots of things to worry, especially pest threats.

Cotton bolls are starting to crack open in the Valley.

“Aphids are showing up in the fields,” Carlos says. “Sticky cotton is the biggest issue for growers.”

Indeed, the valuable cotton fiber is coming out of its protective shell. Heavy aphid and whitefly populations could lead to costly sticky cotton, which severely impacts the fiber quality.

Right now, Carlos is finding an increase in aphid populations in some fields. He stresses the importance of weekly monitoring.

Here’s how UC IPM’s guide to taking samples for aphids as well as whitefly after the first open boll:

“Beginning at least 50 paces into the field, choose a sample plant at random and select the fifth mainstem node leaf from the terminal. Using a hand lens, turn the leave over and check for insects on the underside. Count and record the number and color – either yellow or black aphids.

Sampling for aphids and whitefly is important as bolls open up.

“If three or more whitefly adults are found, then the leaf should be counted as infested. For whitefly, the threshold is 40 percent of the leaves are infested. The treatment threshold during this time is five to 10 aphids per fifth mainstem node.”

 

Meanwhile, Carlos says alfalfa growers are starting to harvest again. A few already have finished cutting and started irrigating for another harvest. Cowpea aphids are worms are the main pest threats. So far, their numbers haven’t reached the threshold for treatment.

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 [MG1]What does this mean white or black? Aphids or whielflies or different types of aphids?