Devastating disease a threat to citrus worldwide

  A citrus pest that carries a devastating new disease hasn't arrived in Yuma County yet, but it's likely only a matter of time, those in the industry fear.

  And it could very well make its first appearance in someone's backyard.

  That's what happened in Florida, where $20 million a year is being spent on research to try to contain and manage Huanglongbing, or citrus greening disease, and the tiny Asian citrus psyllid that spreads the disease, said John Loghry, manager of the Yuma County Citrus Pest Control District.

  He said the problem is so severe that marketing money is being used for research because the belief is that if the disease can't be contained, Florida won't have a crop to market.

  First found in Florida in 2005 in a backyard tree, the disease has since been confirmed in commercial groves many miles away and even neighboring states, said Tim Gottwald, a plant pathology researcher with the U.S. Department of Agriculture in  Florida.

  Gottwald recently gave a presentation on the disease for Yuma-area growers and agriculture officials.

    Hanging in the balance for Yuma County is its citrus industry valued at more than $23 million, according to the Arizona Department of Agriculture.

  The disease usually kills infected trees within a few years. So far there is no known cure, Gottwald said.
  He referred to the disease as "the sleeping dragon" because by the time a tree shows symptoms of the disease, it has already been infected for a while and, if fed on by the psyllid, a source of infection to other trees.

  That's what makes controlling the disease so difficult, he said. For one thing, it's probably too late to save surrounding trees by the time the disease manifests itself because it has already spread. And by the time any biological or chemical control of the psyllid could take effect, the insect likely has already spread the disease.

  "It's a very fast moving disease," he said. That's through an infected tree itself and to other trees that might be miles away. Diseased trees produce bitter, inedible, misshapen fruit and eventually die.

  The only hope at this point, said Gottwald, lies in finding a genetic resistance. "A lot of labs are working on that."

  It's a disease of worldwide concern that threatens citrus-producing areas around the globe, he said. It has wiped out groves from China to Brazil, threatens the Florida citrus industry and now has been found in other Southern states.

  Last summer, the psyllid was found in trees in Tijuana and San Diego, but to date no sign of the disease has been found there, Loghry said.

  Still, growers and agriculture officials here are concerned.

  "At this point, we're being vigilant," Loghry said. "We're keeping an eye on groves near the Mexican border where we think we will see it first."

  The district also is surveying the parameters of the district and checking traps for the psyllid as it checks for other citrus pests, he said. Growers also are encouraged to be on the lookout for the insect.

  "But it could as easily show up in a residential area," he said, perhaps introduced by infected plant material someone brought in from another state.

  He urged people to buy plants only from reputable nurseries certified to be pest- and disease-free.

  "It will be a real challenge to the industry,"  Loghry said of the disease. "There's a lot of research going on."

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Joyce Lobeck can be reached at jlobeck@yumasun.com or 539-6853.