Researchers found use of kaolin particle film on trees reduced populations of HLB-spreading psyllids and delayed HLB infection.
University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) assistant professor Christopher Vincent presented his research comparing red and white kaolin particle films with foliar insecticides during a recent UF/IFAS OJ Break webinar.
According to Vincent, the particles of kaolin clay form a thin residue that coat the leaves of the citrus tree, reflecting light and hiding the green color of the leaves that attract psyllids. Vincent says that both white kaolin and red kaolin applications “had very low psyllid numbers” compared to a foliar insecticide treatment and an untreated control.
He describes white kaolin as a natural product that is commercially available and red kaolin as white kaolin that is dyed to make it pink in color. Red kaolin is not yet commercially available.
“In our experimental plots in Florida, which were under high disease and psyllid pressure, both white and red kaolin reduced psyllid populations by more than 80 percent compared to monthly foliar insecticide treatments,” Vincent says.
He also reports that the red kaolin reduced psyllid populations by about 5 percent more than white. Furthermore, both treatments had positive effects on young tree growth. Kaolin-treated tree trunks had nearly double the girth and much larger and denser canopies compared to untreated trees.
Additionally, Vincent’s research showed both types of kaolin reduced sunburn, improved tree productivity and reduced water loss, keeping leaf temperatures within an optimal range.
Vincent says the main drawback of using kaolin particle films is rain. Frequent rains tend to wash off the films, which are only effective when they are coating the entire leaf. To maintain constant coverage in Florida, growers have reported needing to apply the particle film every two weeks on average. Kaolin typically costs around $40 to $50 per acre, per application, so frequent reapplication is not financially ideal. To resolve this issue, researchers are looking at new dye techniques to improve kaolin’s ability to withstand rainfall.
Read more about Vincent’s kaolin research here.
This article was written by Ashley Robinson, AgNet Media communications intern in Gainesville, Florida.