McALLEN, Texas (AP) -- The vast majority of Texas' commercial citrus groves now reside in expanded quarantine areas aimed at slowing the spread of a disease decimating citrus around the world.
The state Department of Agriculture expanded the citrus greening quarantine areas in South Texas on Monday to cover Hidalgo and Cameron counties. Only a small amount of commercial citrus grown in Willacy County remains outside the current quarantine.
It was the agency's fifth expansion of the quarantine since the first was declared in January 2012, on a 5-mile radius around infected trees in San Juan. The quarantine imposes restrictions on how citrus plants and plant materials can be moved.
The bacterium is carried from an infected tree to healthy ones by the Asian citrus psyllid, a tiny brown insect that showed up in Florida in 1998. The bacterium spreads through an infected tree's vascular system. Trees produce smaller fruit that drops to the ground prematurely, and eventually the trees die. It is not a threat to humans.
Nearly all of the 25,000 acres of commercial citrus planted in Texas are in Hidalgo and Cameron counties in the state's southernmost tip. Before this most recent expansion, about 12,000 acres — or approximately half of the state's commercial groves — were in the quarantined areas, said Texas Citrus Mutual President Ray Prewett.
Only seven groves have been confirmed to have infected trees, representing about 100 acres, but authorities and growers are trying to be proactive, Prewett said. Infected trees have also been identified at 33 residential sites. When found, they are removed.
"The disease is not what you would call widespread (in Texas)," Prewett said.
But its rapid and broad spread through Florida — the country's largest citrus producer — is a stark image of what could happen. The disease was also confirmed in California, the nation's second largest citrus producer, in 2012.
Prewett said one of the biggest concerns is with nurseries. The psyllids do not travel great distances on their own, but if a plant with infected pysillids is moved into an otherwise healthy grove or into a backyard adjacent to a grove, the disease can spread. Since it can take two years for symptoms to appear on the plant after its infection, there's also the possibility that young trees that appear healthy could carry the disease into uninfected areas.
Texas passed legislation in 2013 that required nurseries to grow new citrus trees in indoor, psyllid-free environments, Prewett said. But there were many plants that were already in existence that were grandfathered in and are now being inventoried.