The USDA Horticultural Research Lab in Ft. Pierce has marshaled its resources in recent years to help in the battle against citrus greening (HLB). While the disease was first officially identified in Florida in 2005, Dr. Tim Gottwald, plant pathology research leader at the lab, has been studying the disease for many years in countries where it is present including India, China, South Africa, and Brazil.
When greening was confirmed in Florida, Gottwald predicted, based on his previous knowledge, infected trees could die within three to four years and that the disease would spread across the state in about the same timeframe.
According to Dr. Calvin Arnold, laboratory director in Ft. Pierce, Gottwald’s predictions have unfortunately turned out to be true. He says because of the threat posed by citrus greening, the research facility redirected resources toward greening study.
“When HLB was confirmed, we looked very closely at our research with encouragement from growers and industry,” he says. “We began moving resources from programs, especially from CVT and diaprepes root weevil to HLB research. Since then our HLB research has expanded rapidly and we remain heavily committed to the program.”
Approximately 60% of all the research conducted at the Ft. Pierce facility is focused on citrus and 75% of the citrus research is focused on greening. There are about 40 active projects at the lab focused on the disease, each with multiple experiments under way in the lab, growth chambers, or in the field. According to Arnold, roughly half of the scientists at the lab are working on greening research.
Signs Of Promise
Researchers at USDA are using the same technology in hopes of targeting the psyllid. Wayne Hunter is conducting the RNAi research which aims to disrupt psyllids. He says the approach is very attractive because it is a natural approach that would only target the psyllid, leaving beneficial insects in the groves to do their work.
Map It Out
“We are within a couple of months of identifying the complete genetic sequence of the psyllid,” says Arnold. “Dr. Yong-Ping Duan led a team of researchers here in Ft. Pierce to map out the genome of the HLB bacteria a couple of years ago. These are huge breakthroughs in the science of fighting greening.”
There are a number of antibiotics — when placed in direct contact with the HLB bacteria — that will kill it. The challenge is finding an antibiotic that will move through the phloem tissue of trees and access the HLB bacteria in all areas where it is present.
Loud And Clear