In Florida the disease has spread to all parts of the state threatening to cripple a $9 billion-a-year industry that supplies 90 percent of U.S. orange juice. The Florida Department of Citrus predicts that citrus greening will cut Florida orange production by 5 percent to 6 percent a year until a cure is found or disease-resistant trees are developed and widely planted. That translates into cutting orange production nearly in half over the next decade.

Citrus greening is widespread in Brazil, Cuba, Belize, and southern Mexico and four U.S. states (Florida, Louisiana. South Carolina, Georgia) – but so far the disease has not been detected in either California or Texas, although the Asian citrus psyllid (ACP) is widespread in both states. The psyllid is also found in Alabama, Arizona, Florida, Georgia, Hawaii, Louisiana, Mississippi, and South Carolina.

While there have been no confirmed reports of citrus greening in Texas or California, Dr. John da Graca, a plant pathologist and director of the Texas A&M-Kingsville Citrus Center in Weslaco, a USDA citrus testing facility, says the Asian psyllid is well rooted in both states.

“In the (Texas) Rio Grande Valley alone we have confirmed large populations of the psyllid, first detected in 2001. By 2006 we detected psyllid populations in the Big Bend area, in College Station and the Houston area, and many areas south of that line that divides the state into north and south regions,” da Graca reports.

Da Graca agrees with Hawkins that Texas and California commercial growers are doing a good job in monitoring orchards for signs of the disease and are actively involved in prevention planning and attempts to control psyllid populations. He says the greatest threat of outbreak in the state comes from infiltration of nursery stock and cuttings from infected tress and plants from out of state, a problem Hawkins says is a challenge.

Greatest threat

“Our greatest threat is from an infected tree, plant or cutting entering the state by consumers. Unknowing residents might purchase ornamentals or nursery stock from unscrupulous sellers either through a Web site or by unknowingly purchasing an infected product out of state and bringing it back for use in their yard or garden. Once an infected plant takes root, it is subject to psyllid transmission,” Hawkins says.

Pathologists at the Texas A&M-Kingville Citrus Center are currently studying methods of developing citrus greening resistant trees in hopes of one day providing an effective method of replacing non-resistant varieties as a way to eradicate the disease, but they agree it may be years or decades before that can happen.

In addition, da Graca says a method of applying a “nutrient cocktail” to non-resistant plants is being tested in Florida, Texas and California and has demonstrated promising results.

“We have been testing this and other methods of controlling the disease and have experienced some success. But such experimental methods of fighting the spread of the disease are still a few years away before widespread application will become effective. Until then we are actively promoting psyllid control and insect reduction in hopes of staying ahead of the game, but to think Texas or California will escape citrus greening infection in the months and years ahead are “optimistic” at best,” da Graca says. “The best method of control currently is an informed public.”

More information about citrus greening can be found at www.texascitrucgreening.org.