These Valencia trees in Texas show good growth five years after HLB was confirmed in this grove. At the time of infection, the grower removed approximately one-third of his trees.
John da Graca, director of the Texas A&M University Kingsville Citrus Center in Weslaco, was among hundreds attending the International Research Conference on HLB March 15-17 in Orlando. He summarizes the Texas industry’s experience with HLB and the Asian citrus psyllids that spread the disease.
“Psyllids arrived (in Texas) about 2001,” da Graca says. “At the time it wasn’t seen as a major pest, so little was done on it.” He notes that HLB wasn’t discovered in Florida, the first state infected, until 2005.
John da Graca
When Texas began surveying for psyllids and HLB, “We found the psyllids pretty well everywhere we looked,” he says, even in Houston and San Antonio, far from the Lower Rio Grande Citrus Belt.
“In December 2011, one of the (U.S. Department of Agriculture) inspectors noticed a tree at the edge of an orchard that looked suspicious,” da Graca recalls. Samples were taken, and HLB disease was confirmed in early 2012.
A number of trees in that orchard were infected, and the grower agreed to remove a third of his orchard. “He’s now doing a better job of managing the citrus pest control, disease control and fertilization,” da Graca says. “And in the remaining two-thirds of the orchard … five years later, he is making a good living out of those trees.”
“We know the disease is spreading,” da Graca says. In addition to good cultural practices in individual orchards, growers have coordinated area-wide spraying programs for psyllids during dormant periods (November and/or February as well as August). The sprays have dramatically reduced psyllid populations.
“Our (psyllid) populations have never been as high as they’ve seen in Florida,” da Graca says. “We suspect that’s because the climates are different and the soils are different in Florida … In Texas, there are local conditions which make it a little bit tougher for the psyllids, and by spraying at the right times, we’ve achieved about the best psyllid control that we could have.”
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