“It's like having an embarrassing social disease,” Betancourt said. “We want to do better, and we need your help.”
Betancourt was appealing to UC Agriculture and Natural Resources and other experts who were gathered with him at the California Cotton Ginners and Growers Association annual meeting in Visalia. UC ANR entomology specialist Larry Godfrey had begun the pest management session with a somber message. The whiteflies that cotton growers had been controlling reasonably well for more than 20 years was suddenly posing a tremendous challenge.
“I don't know what's up,” said Godfrey, who is housed in the Department of Entomology and Nematology at UC Davis. “It's a different critter.”
Betancourt attested to Godfrey's conclusions. He observed a few whiteflies in the field during the summer of 2013. It was a minor problem. In 2014, he decided to be more aggressive with monitoring and treating for the pest.
“I doubled down last year, but we had a bigger problem with whiteflies,” he said. “I thought, ‘This just can't happen!'”
Whiteflies feed on plant sap and then excrete honeydew. The sweet, sticky honeydew settles on open cotton bolls. If sticky cotton makes its way to spinning mills, it gums up the machinery. It's a scenario that mill managers won't soon forget.
Because of the San Joaquin Valley's long, dry growing season, cotton farmers have earned a reputation for high-quality, high value cotton, said Roger Isom, the CEO of the California Cotton Growers and Ginners Association. Sticky cotton is major concern.
“It happened in Arizona and almost destroyed the state's cotton industry,” Isom said. “Sticky cotton brings mills to a standstill. If they start getting sticky cotton, they'll decide to stop buying from the area where it came from. And once you have the stigma, it's extremely hard to overcome.”
Godfrey said the new biotype of sweet potato whitefly was first found in the San Joaquin Valley in July 1992. Certain areas required careful management, such as those closer to cities where it is warmer and the pest can spend the winter on ornamental plants. Farmers were able to deal with it.
“Then, in 2013 and 2014, populations of whitefly developed in other parts of the San Joaquin Valley, not only adjacent to cities. We don't know why or exactly what is going on,” Godfrey said.
Initially, pest control advisers suspected the whitefly was developing pesticide resistance. UC ANR research trials at the UC West Side Research and Extension Center in Five Points and the Shafter Research Station in Kern County showed that insecticides used at label rates were still able to knock down the pest.
“What we did notice was we had a lot more whitefly and we started seeing them earlier than normal,” Godfrey said. “It certainly makes it more expensive to grow cotton and, if not controlled, makes sticky cotton.”
What's worse, the reputation of cotton in a whole area is tarnished if one or two farmers mismanage the pest and their cotton gets into commercial channels.
“In my area, we have a problem right now and it's not just my problem,” Betancourt said. “Everybody who has whiteflies has to deal with them. We have a reputation to uphold.”
All the growers who send cotton to the same gin as Betancourt will be invited to meet with UC ANR scientists Godfrey and Pete Goodell, integrated pest management advisor, to strategize about whitefly control for 2015.
Godfrey said they will emphasize the importance of early management and treatment, sharing lessons learned in Arizona.
“The scientists there did a lot of really good work on quantifying an infestation and determining when to treat,” Godfrey said. “We are taking their recommendations and studying where we might need to make changes due to California growing conditions.”
Goodell said it is critically important for growers to take the threat of sticky cotton seriously.
“We can't reiterate enough, once you develop a poor reputation for sticky cotton, it sticks with you,” Goodell said.
An initiative to manage endemic and invasive pests and diseases is part of UC Agriculture and Natural Resources Strategic Vision 2025.
Goodell webinar on Preventing Sticky Cotton.
Godfrey research report PDF attached below: