WESLACO — Citrus does more than create jobs and pump money into the economy of the Lower Rio Grande Valley. It’s a way of life, a cultural staple dating back 100 years, part of the landscape and fabric of what makes extreme South Texas what it is, according to a plant disease expert. He’s now asking the people of the Valley to help keep the citrus industry from disappearing.
“We can see what’s happening to the citrus industry in Florida,” said Dr. Olufemi Alabi, a Texas A&M AgriLife Extension Service plant pathologist at the Texas A&M AgriLife Research and Extension Center at Weslaco. “The citrus industry in Florida is fast collapsing, due to a devastating disease called huanglongbing, or citrus greening. But here in South Texas, we can still fight this thing.”
(click on the video below for tips on how the public can help)
The Rio Grande Valley’s citrus industry employs more than 1,000 people, earns growers $72 million annually, and has an economic impact of $134 million, according to Dr. Luis Ribera, an AgriLife Extension agricultural economist in Weslaco.
Citrus greening disease, which doesn’t harm humans but can wipe out entire orchards, has been found recently in a third area of the Valley, in La Blanca, a few miles east of Edinburg, on residential property. The bacterial disease has no cure yet, but Alabi believes that if everybody does their part, the Valley’s citrus industry can be saved.
Citrus greening symptoms mimic those of a tree that lacks water or nutrients, but only an expert can tell the difference, Alabi said. And Asian citrus psyllids, small insects the size of a mosquito that appear to have their tails sticking up in the air, spread the disease from tree to tree. The public’s help is needed to keep the disease and its vector at bay.
“First of all, don’t move citrus plant material around without being certain of their health status,” he said. “If someone among us has malaria, for example, we want to isolate and treat that person so that nobody else gets sick, right? Well, it’s the same with citrus greening disease. Don’t take any chances because one infected tree can serve as a source of disease for hundreds or thousands of trees. Don’t take citrus plants to a friend, either across town or across the Valley if you are unsure of their health status, just to stay on the safe side.”
Second, when buying citrus trees for retail, commercial or residential use, make sure they are certified free of greening, Alabi said.
“Retail and wholesale nurseries are required to follow state-mandated guidelines to make sure they are selling only healthy trees,” he said. “Don’t buy citrus trees from a roadside vendor or at a flea market. Buy only trees that are clearly tagged as inspected and certified.”
And third, if your citrus tree doesn’t look healthy, call an expert to come check it.
“That’s what we’re here for,” Alabi said. “If we get a phone call from a citizen saying their tree looks sick, or if they have an infestation of Asian citrus psyllids on a tree, we have an obligation to go check that tree.
“These psyllids (pronounced SILL-ids) are easy to spot and they must be exterminated, eradicated, but don’t depend on a neighbor or store salesperson to tell you how to do it,” he said. “Call us. We’ll evaluate the insect problem and tell you how to proceed.”
Anybody with questions is urged to call either the Weslaco Center at 956-968-5585, or the Texas A&M-Kingsville Citrus Center at Weslaco at 956-447-3360.
“Thanks to the backing of our local citrus industry and additional resources from relevant federal and state agencies, we have a state-of-the-art testing laboratory at the Citrus Center at Weslaco,” he said. “The lab, directed by Dr. M. Kunta, can run tests on plant tissue and insect samples to determine if the citrus greening bacterium is present or not.”
The Texas Plant Disease Diagnostic Laboratory in College Station is also equipped and certified to run tests on suspected trees, Alabi said. The websites for the two labs are http://citruscenter.tamu.edu/diagnostic.html and http://plantclinic.tamu.edu, respectively.
Surveys conducted by the Citrus Center and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service have resulted in three finds of citrus greening in the Valley, Alabi said.
The first case was found in a commercial grove south of San Juan in 2012, followed by other finds on nearby residential properties. The second hotspot was found on residential property in Mission in September, 2013.
And a third case of citrus greening was reported this month in a residential area in La Blanca, emphasizing the importance of active monitoring for the disease, Alabi said. Each find has prompted quarantines of all citrus within a 5-mile radius of the infected tree by the Texas Department of Agriculture. The quarantine prohibits the movement of live trees from those areas.
“They pose a very high risk to commercial groves because this disease is spread from tree to tree by an insect that does not discriminate between commercial and residential trees,” he said.
So far, some 100 trees have tested positive for citrus greening disease, all of which have been destroyed, Alabi said.
“People have been very cooperative in destroying these diseased trees, which is very important because if allowed to persist, those trees serve as a source of the bacterium,” he said. “Psyllids could land on that tree, pick up the disease and spread it to other trees until the problem is widespread. Sacrificing one tree can save thousands of other trees.”
Alabi said that while several psyllids have tested positive for citrus greening in other areas besides the three confirmed finds, nearby trees have not tested positive.
“It’s an ongoing process,” he said. “Trees and insects are being surveyed and tested daily. And growers are doing all they can to keep psyllid populations in check. But again, it’s all voluntary. It has to be an area-wide effort and an encouragement of good neighborliness because if area A, for example, is being treated for psyllids but area B is not, area A remains at risk.”
Another battle against the insect that spreads the disease is the mass release of another insect that feeds on psyllids.
“This is the second year in which populations of Tamarixia radiata are being released to control the psyllids non-chemically,” he said. “This effort is spearheaded by Dr. Daniel Flores with USDA-APHIS’s Plant Protection and Quarantine. It has proven very effective, but the challenge is to rear and release sufficient numbers of these tiny wasps to try and control the psyllid populations.”
Drs. Mamoudou Setamou and Andrew Chow, entomologists at the Citrus Center, are conducting research of a fungus that feeds on and destroys psyllids.
Dr. Erik Mirkov, an AgriLife Research plant pathologist in Weslaco, is currently field testing citrus trees with genes from spinach that show resistance to greening. And Dr. Eliezer Louzada, a plant breeder at the Citrus Center, is working to determine potential sources of natural resistance to the bacterium.
Others involved in efforts to combat greening include the Texas Citrus Producers Board, the Texas Department of Agriculture, USDA-APHIS-PPQ, other scientists and staff at the Citrus Center and Texas A&M University.
“The public can, and must, play a vital role in saving the Valley’s citrus industry,” Alabi said. “If you see a tree that doesn’t look right, or if you see infestation of an insect that could be an Asian citrus psyllid, we’re just a phone call away: 956-447-3360 or 956-968-5585.
“We want to know about your tree and we will come inspect it.”