• The beet curly top virus caused serious damage to the San Joaquin Valley’s tomato crop in 2013.
• A high population of the beet leafhopper has farmers and state agriculture officials concerned.
• The state is applying insecticides to more than 50,000 acres to keep the leafhopper under control.
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A plant virus that wrecked the central San Joaquin Valley’s tomato crop in 2013 could be making a comeback, experts say.
Recent inspections in Fresno and Kings counties have turned up a high number of beet leafhoppers, the insect responsible for spreading beet curly top virus.
The virus is a nasty disease that causes plant leaves to curl, leading to stunted growth and poor yields. It also can be deadly to seedlings.
“We are not ringing the alarm bells and telling people not to plant if they don’t have to,” said Chuck Rivara, director of the California Tomato Research Institute. “But we are worried.”
Rivara, farmers and state officials said the conditions for spreading the disease are similar to 2013: many leafhoppers and an ample supply of weeds. Although California may be in its fourth year of a drought, a few well-timed rainstorms helped a strong crop of weeds sprout in the Coast Range hills.
In early March, inspectors with the state’s Beet Curly Top Virus Control Program found an unusually high number of insects. Counts averaged 30 to 50 adult insects per 10 net sweeps. A normal spring would yield an average of 10 to 12 adult insects per 10 sweeps. One area had counts as high as 100 beet leafhoppers.
As a result, the state is treating hot spots in Fresno and Kings counties where the beet leafhopper counts are extremely high. The program has identified 54,974 acres to be treated so far, state records show. Earlier this year, the state treated areas with high bug populations for the first time since 2006.
Steve Lyle, spokesman for the California Department of Food and Agriculture, said the high numbers are a concern.
“The more leafhoppers, the more damage,” Lyle said. “The level of damage also depends on the amount of virus in the hoppers.”
Last month in Fresno County, 32 leafhoppers were collected and six of them tested positive for curly top virus.
In the Valley, which is the nation’s leading supplier of processing tomatoes, the virus caused significant losses during the 2013 season. Tomato industry officials estimate the virus knocked out 1 billion tons of tomatoes from the 13 million tons harvested that year.
Processing tomatoes are used in sauces, paste and other food ingredients. Fresno County is California’s leading grower of processing tomatoes.
West-side tomato farmer Alan Sano said he is concerned about a possible return of the curly top virus. “We know that once the foothills start drying up, the leafhoppers will start looking for something to eat. We have to get control of this early.”
Ironically, the beet leafhopper isn’t a big fan of the tomato plant, but the bugs’ finickiness helps spread the disease, said Brenna Aegerter, San Joaquin County farm adviser specializing in vegetable crops.
“They just keep moving from plant to plant,” she said. “And if they have the virus, they will transmit it to every plant they feed on.”