Citrus viruses a real threat – Porterville Recorder
For many years, Vic Corkins and his Central California Tristeza Eradication Agency (CCTEA) team were the self-proclaimed “guys in the black hats.”
Today, they’re the “guys in the white hats.”
While the approach of the CCTEA — formed in 1963 and charged with the survey, detection and eradication of a virulent strain of the citrus disease tristeza — has changed, its mission has remained the same for nearly half a century: to protect the San Joaquin Valley’s multi-billion-dollar citrus industry.
Transmitted by the brown citrus aphid, tristeza, which means “sadness” in Spanish, is a devastating disease that causes quick decline by choking off the bud union of citrus trees and starving their roots.
A worldwide problem, the virus essentially wiped out commercial citrus production in Orange County in the 1960s. It especially infects trees that are grafted onto sour orange rootstocks.
Up until just three years ago, the CCTEA, a grower-funded agency that now does business as the broader Citrus Pest Detection Program, mandated the removal of citrus trees infected with tristeza.
“It was a hard battle, going out and telling a grower, ‘You have to take that tree out. We found tristeza in there.’ Yet the tree was making them money,” said Corkins, the agency’s operations coordinator.
Not surprisingly, Corkins and the CCTEA landed in court several times with angry growers sitting at the plaintiff’s desk.
Today, however, because the virus was so rampant and mandating the complete removal of tristeza-infected trees was an unrealistic goal, the CCTEA’s approach is different.
Now, the agency targets MCA13, a virulent strain of tristeza that can adversely affect all rootstocks — not just sour orange — by causing seedling yellows and stem pitting.
Leaves from growers’ orchards are collected by CCTEA crews and taken back to the agency in Tulare, where the samples are run through a series of tests to determine if they’re MCA13-positive.
“We’re no longer mandating the removal of trees with the polyclonal virus that causes quick decline on sour orange rootstocks,” Corkins said. “I think that’s much to the growers’ satisfaction.”
The CCTEA does, however, mandate the removal of MCA13-positive trees. Luckily for growers, MCA13 is “not a big threat” in Tulare County’s $616 million citrus belt, Corkins said.
“If you don’t take it out, it’s one of those things that will become a threat,” he said.
The CCTEA is funded by growers in three districts — Southern Tulare, Kern and Central Valley. Last year, the CCTEA mandated the removal of only about 25 trees in these districts, Corkins said.
Two other districts — Tulare County and West Fresno — work with the CCTEA but on a much smaller scale.
“The growers are very amenable in pulling out a tree with MCA13 because there might be one in a hundred acres,” Corkins said.
The growers in each district pay an assessment, based on every 100-tree acre, that is collected through their property taxes.
Each district has the option of reimbursing the grower up to $25 for each uprooted tree.
“Twenty-five dollars is really inadequate when you look at pulling a tree out, replacing it and lost production for about seven years until you break even,” Corkins said. “That was part of the contention and the unpopularity of the program. You can imagine the pushback on that sort of thing.”
But Corkins said he believes the CCTEA, which is comprised of a board of directors who are appointed by the Tulare County Board of Supervisors, is heading in the right direction now with a realistic goal in mind.
Also, because the CCTEA now operates as the Citrus Pest Detection Program, it is not limited in which viruses it can study and work to control.
For example, Corkins said if the Huanglongbing (HLB) virus ever penetrates the Valley, the CCTEA will be able to develop a plan to combat it.
Corkins said 40 percent of Florida’s citrus industry has been destroyed by HLB, which also has a presence in Mexico.
“[HLB] is really a major focus with the growers right now. That’s a major thing,” Corkins said. “If we get it up here, all of the focus will be on HLB, I’m sure.”
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