Cotton Farming

Offering a bit of good news to the beleaguered cotton industry, UC integrated pest management advisor Pete Goodell predicts the number of lygus bugs that will threaten San Joaquin Valley cotton early this season will be light to moderate.

"Our first hurdle is avoiding damage during the earliest portion of the fruiting cycle," Goodell said. "Judging from the monitoring our spotters have been doing during the last several weeks, it appears that farmers should be in good shape during this critical stage of cotton development."

The severity of lygus bugs in any year depends on the complex interaction of weather, availability of hosts and the length of mating periods. For 16 years Goodell has projected lygus infestation in the San Joaquin Valley by monitoring roadside plants each spring with sweep nets. This year 30 spotters are participating in valley lygus monitoring.

Goodell said he believes lygus populations are low this year because of a December-to-January dry spell during the typically rainy winter, the unseasonably cool early spring and unseasonably hot late spring.

"Based on our surveys in April and May, host plants were unevenly distributed around the edge of the San Joaquin Valley," Goodell said. "Tarweed, the most common host, quickly dried in the May heat and became unavailable before lygus could complete its life cycle."

The lygus prediction is welcome news for cotton farmers, who are entering the season faced with high energy and water costs and low commodity prices. Additionally, the cool early spring temperatures delayed cotton planting and development.

"Farmers are anxiously waiting for the first fruiting buds," Goodell said. "They can't afford to use any treatments that are unnecessary. Close monitoring for lygus bugs will indicate whether or not treatment is necessary."

Mid- and late-season populations of lygus in individual cotton fields will depend on local factors, Goodell said. He urges growers and pest control advisers to consider the cropping mosaic in which cotton fields are located and begin formulating a strategy for dealing with movement from adjacent crops, such as tomatoes, sugar beets, seed alfalfa and alfalfa hay.

"Farmers and PCAs should be sure they understand where the threat might develop and what tactics might be employed to mitigate large movements of lygus," Goodell said.

Based on UC guidelines, lygus densities during late June and July should exceed 7 bugs in 50 sweeps with at least 1 nymph present in the sample before treatments are considered.
#

Jeannette Warnert
Sr. Public Information Representative
UC Ag and Natural Resources
550 E. Shaw Ave.
Fresno, CA 93710

Early-season Lygus Will Be Light To Moderate In The San Joaquin Valley
Offering a bit of good news to the beleaguered cotton industry, UC integrated pest management advisor Pete Goodell predicts the number of lygus bugs that will threaten San Joaquin Valley cotton early this season will be light to moderate. "Our first hurdle is avoiding damage during the earliest portion of the fruiting cycle," Goodell said. "Judging from the monitoring our spotters have been doing during the last several weeks, it appears that farmers should be in good shape during this critical stage of cotton development." The severity of lygus bugs in any year depends on the complex interaction of weather, availability of hosts and the length of mating periods. For 16 years Goodell has projected lygus infestation in the San Joaquin Valley by monitoring roadside plants each spring with sweep nets. This year 30 spotters are participating in valley lygus monitoring. Goodell said he believes lygus populations are low this year because of a December-to-January dry spell during the typically rainy winter, the unseasonably cool early spring and unseasonably hot late spring. "Based on our surveys in April and May, host plants were unevenly distributed around the edge of the San Joaquin Valley," Goodell said. "Tarweed, the most common host, quickly dried in the May heat and became unavailable before lygus could complete its life cycle." The lygus prediction is welcome news for cotton farmers, who are entering the season faced with high energy and water costs and low commodity prices. Additionally, the cool early spring temperatures delayed cotton planting and development. "Farmers are anxiously waiting for the first fruiting buds," Goodell said. "They can't afford to use any treatments that are unnecessary. Close monitoring for lygus bugs will indicate whether or not treatment is necessary." Mid- and late-season populations of lygus in individual cotton fields will depend on local factors, Goodell said. He urges growers and pest control advisers to consider the cropping mosaic in which cotton fields are located and begin formulating a strategy for dealing with movement from adjacent crops, such as tomatoes, sugar beets, seed alfalfa and alfalfa hay. "Farmers and PCAs should be sure they understand where the threat might develop and what tactics might be employed to mitigate large movements of lygus," Goodell said. Based on UC guidelines, lygus densities during late June and July should exceed 7 bugs in 50 sweeps with at least 1 nymph present in the sample before treatments are considered. # Jeannette Warnert Sr. Public Information Representative UC Ag and Natural Resources 550 E. Shaw Ave. Fresno, CA 93710
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