Devastating citrus disease hits U.S. for first time in Tulare County

The incurable Citrus Yellow Vein Clearing Virus is found for the first time in the U.S. on residential properties in Tulare after routine inspection

TULARE – For the first time ever, a citrus tree disease known as the Citrus Yellow Vein Clearing Virus was found in the United States during a farm inspection in Tulare. 

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of the Citrus Yellow Vein Clearing Virus (CYVCV) on a farm in Tulare during a routine inspection. This virus has never been found in the Americas before. CYVCV is untreatable and can cause significant economic loss and decrease in fruit production, according to the California Department of Food and Agriculture (CDFA).

“CYVC is an emerging disease causing escalating economic losses in multiple citrus species and varieties,” the CDFA website states. “This is a disease of quarantine significance to the United States.”

Citrus Research Board’s Chief Research Scientist Melinda Klein said that there is little information on how the nation or state will cure and address the virus, as it is so new to the region. Klein said APHIS and the U.S. Department of Agriculture are taking the lead in investigating the virus and according to CDFA are at an information gathering stage. 

The first step will be to measure the spread of the virus to surrounding regions such as Fresno and Kings counties. Klein said there are also no research plans being conducted yet until the state understands how widespread the virus is.

“The virus may not reveal a lot of symptoms right now, because it seems to be heat sensitive, but as we cool off into the fall, if people see any kind of unusual symptoms, we would encourage them to speak with CDFA,” Klein said.

The cause of it reaching the U.S. is still unknown, though CYVCV is spread through aphids, tree grafting and using equipment that was not cleaned after being exposed to the virus. As far as the CFDA knows, CYVCV cannot be controlled or cured, only prevented.

The symptoms of CYVCV are similar in most countries, with China experiencing leaves that appeared “water-soaked,” with clear and yellow veins stretching across the warped citrus leaves. The virus weakens in the heat but worsens in colder climates. The appearance of these symptoms varies on temperature and location of these trees, and in some cases can cause mosaic-like structures on the fruit body, or ring spots on leaves, according to the CDFA.

CYVCV was first discovered in Pakistan in 1988 and didn’t reach another country until 1997 when it made its way to India. China and Turkey later found the virus in certain areas by the 2000s.

Citrus is a billion-dollar operation in Tulare County, with the Central Valley making up 75% of California’s total citrus production. CYVCV could result in serious economic loss, such as in 2009 when the disease was discovered in the Yunnan province of China and resulted in a 20% decrease in fruit production. 

This isn’t the first concerning agriculture disease to hit Tulare County. In 2018, Tulare County used “aggressive” measures to fight the Asian citrus psyllid (ACP) infestation and prevent huanglongbing (HLB), two devastating threats to the Central Valley’s citrus industry. ACP nymphs were found in Woodlake, Lemon Cove and Vislaia and are known to transmit HLB, which is fatal to trees.

For previous diseases, like ACP and HLB, acres of neglected or old groves were knocked down and multiple pesticides were used to kill the disease. A plan for a CVYVC cure is still underway.

CORRECTION: This article has been corrected to reflect that the Citrus Yellow Vein Clearing Virus was found on residential properties. This article was corrected at 4:24 p.m. pacific time on Friday, Aug. 26

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