Monday, July 22, 2013

Learning to Manage a Sticky Situation in Valley Cotton

Walking through a lush, field of cotton plants, you could feel something tacky on the rich green leaves.
You turn over a leaf for a closer inspection. On the back, you find a fair number of aphids feeding on the back of the leaf.

 In this San Joaquin Valley field, field scout Carlos Silva estimated finding aphids problems on some 40 percent of the leaves he inspected.

With cotton bolls in bloom and displaying a spectacular display of bright yellow and pink flowers, it is time for growers to pay special attention to aphids and whiteflies.
Aphids feeding on the back of a cotton plant leaf.

These pests can eventually affect the quality of the lint and be costly to producers and cotton ginners.

Here’s the problem: When aphids feed on the leaves, for example, they secrete a sticky honeydew-like substance that falls onto leaves and the other parts of the cotton plant. A fungus develops and leaves a black, sooty mold. The worry down the road is the honeydew will get onto the lint and result in economically damaging sticky cotton.

Yes, it’s not too early to be concerned about sticky cotton.  For generations, this issue has been haunting cotton growers across the globe.
A sticky honeydew-like substance coats the leaves.

Observations about pests and sticky cotton date back to the 1930s in India. Sticky cotton can cost growers 3 to 5 cents per pound in revenue annually, according to a 2007 USDA report. At the same time, managing these pests can be expensive.

For example, California cotton growers spent more than $220 million on pest control measures for whiteflies from 1992 to 2001, according to the USDA report written by E. Hequest of Texas Tech University, T.J. Henneberry of the USDA Arid Land Research Center in Arizona and R.L. Nichols, ag research director with Cotton Inc.

 “Cotton stickiness caused by excess sugars on the lint from the plant itself or from insects is a very serious program that affects all segments of the cotton industry. Stickiness is a worldwide contamination problem: Around one-fifth of the world production is affected to some degree,” the researchers point out.

Dirt will gets stuck on the sticky lint. - UC IPM photo
But controlling aphids and whiteflies isn’t a matter of simply spraying chemicals. The USDA report stresses a balanced integrated pest management approach. These pests “have demonstrated a penchant for development resistance to insecticides. Thus, resistance management principles must be integrated into the overall management programs for each of these pests or the risk of early loss modes of insecticide action will be increased.”

If you want to learn more, go to UC IPM online to read about monitoring aphids and whiteflies in cotton. Guess you can say there’s nothing sweet about sticky cotton.

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