- Huanglongbing disease is the HIV of the citrus world, says University of Florida entomologist Michael Rogers.
- HLB is one of the most significant citrus diseases worldwide due to difficulties in disease management.
- HLB-related tree death is usually not caused by the disease alone. A feeding psyllid punctures the tree’s phloem which increases the tree’s susceptibility to other citrus-related pests and diseases which speed up the tree’s decline and eventual death.
RESEARCHERS COLLECT yellow sticky pest traps looking for the Asian citrus psyllid.
HIV of citrus world
“HLB is the HIV of the citrus world,” Rogers stated in his opening remarks. “HLB is considered one of the most significant citrus diseases worldwide due to difficulties in disease management,” Rogers said.
The ACP primarily feeds on new citrus tree flush for reproduction. The adult female psyllid lays eggs on new tree flush. The eggs hatch in three-to-five days. The psyllid life span is 30-to-60 days.
Rogers says HLB-related tree death is usually not caused by the disease alone. HLB disrupts the phloem system of citrus trees which causes a decline in tree health. This makes the trees more susceptible to other diseases, including phytophthora root rot and blight, which combined with HLB greatly speed up the demise of HLB-infected plants.
“The combination of HLB and phytophthora can take out a tree almost overnight,” Rogers said. “Young infected trees decline quickly. A tree can have a full canopy and several days later the leaves have all dropped and the tree is dead.”
HLB infection tree symptoms – yellowed leaves plus multi-colored smaller, off-sized, sour-tasting, unmarketable fruit – may first appear several years after the initial infection.
HLB-disease symptoms can mirror symptoms caused by nutrient deficiency, including low levels of manganese, zinc, and boron.
On average, Rogers says Florida citrus growers apply 8 to 12 insecticidal treatments annually in a standard, mature grove.
Why so many treatments? Foliar-applied insecticides have a short residual period and the insects constantly move, Rogers says. Psyllids generally fly until a suitable host is found. Laboratory windmill studies in Florida suggest the psyllid can sustain flight for more than an hour and fly more than one-and-a-half miles.
“These little guys can disperse over fairly long distances despite their very small, 3-to-4 millimeter adult body size.”
In Brazil, the pest and disease have caused substantial losses in commercial citrus. Producers apply insecticides up to 26 times annually for psyllid control.
Rogers also discussed UF psyllid research insecticide use and other methods to limit psyllid numbers and HLB transmission. In a 2006 UF research trial, psyllid nymphs were targeted during flush with diflubenzuron, fenpyroximate, petroleum oil, abamectin, and other products.