The source of the infestation remains a mystery, although Gilbertson has some theories.
The plants were started from seeds, and tomato yellow leaf curl virus is not a seed-transmitted disease. So it had to come in on infected whiteflies blown in from Mexico, he says.
“These whiteflies are very delicate and can’t fly on their own for more than 7 to 10 miles,” Gilbertson says. “But they can get caught up in wind currents and be blown for several hundred miles. We believewe’re not 100 percent surethese whiteflies were blown into Southern California.”
He says he believes populations of infected whiteflies built up in the Brawley greenhouse, then moved out to residential properties, where they infected plants.
Genetic testing shows the strain of the disease found in the greenhouse is nearly identical to that found in northern Mexico, Gilbertson says.
For more information and to download a flier on the virus, visit the UC IPM Web site at http://www.ipm.ucdavis.edu/PMG/r783103311.html.