Researchers Share Tree Health Suggestions

University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers gave a crowd of growers suggestions that can help keep citrus trees healthy. The panel discussion was part of the Nov. 16 open house and field day at the UF/IFAS Citrus Research and Education Center in Lake Alfred.

HLB-affected trees need enhanced nutrition “throughout the growing season,” said horticulturist Tripti Vashisth. She added that micronutrients are needed at a higher rate than previously thought. Vashisth also said that gibberellic acid, when used properly, can improve tree growth and fruit size while reducing fruit drop.

Trees with HLB have trouble moving water from the soil to the canopy, largely because HLB drastically reduces trees’ root systems, said Christopher Vincent, also a horticulturist. He reported that kaolin clay sprayed on trees essentially provides shade for the canopy and helps maintain water-use efficiency. CREC Director Michael Rogers, who moderated the researchers’ presentations, noted that kaolin clay was initially investigated several years ago for its potential to control HLB-spreading Asian citrus psyllids.

Entomologist Lukasz Stelinski reported that insect populations, including psyllids, shut down natural tree defense mechanisms. He suggested that growers “moderate” psyllid populations before they become high, rather than try to eliminate them. He said by spraying before the first tree flush and then only when psyllid populations rise to certain levels, growers can obtain adequate psyllid control. When HLB was first discovered in Florida in 2005, growers often sprayed many more times per year, which added to drastically increased production costs. Learn more from Stelinski about managing psyllids at reduced cost.

Just before the researchers made their presentations, Scott Angle, who leads UF/IFAS, said more citrus research is conducted at the CREC “than anywhere else in the world.” He said UF/IFAS’ job is to help growers be profitable. “We can’t affect market price” but can help growers reduce input costs, he said. “I know we have not made enough progress on HLB,” he said, adding that UF/IFAS will continue to give growers management tools to help them cope with the disease.