Kaolin effectively controls whitefly in beans

The authors of the study in HortScience said previous experiments in temperate regions have shown that kaolin foliar sprays have insecticidal attributes. "However, this type of research in tropical areas, specifically in Andean regions, is virtually nonexistent," they noted. The researchers from Universidad Nacional de Colombia studied the greenhouse whitefly Trialeurodes vaporariorum (Westwood), one of the most prevalent pests in the region's bean crops. The study design consisted of three experiments using four treatments: no insecticide (control), synthetic chemical insecticides, foliar applications of kaolin at 2.5%, and foliar applications of kaolin at 5% (weight/volume).

Foliar applications of kaolin at both doses controlled ≈80% of the population of whitefly in different stages (eggs, nymphs, and adults) in all three experiments. Analyses showed that the percentage of efficacy of the two doses of kaolin was similar to that obtained in bean plants treated with synthetic chemical insecticides (90%).

The study also showed kaolin doses at 5% produced positive effects on the bean plant physiology, causing a 40% reduction in transpiration and an increase of 43% in leaf chlorophyll content compared with untreated plants.

"We can suggest that the use of kaolin can be considered as an alternative to control whitefly, T. vaporariorum, without any negative effect on seed yield," the authors said. They added that kaolin may also help the plant physiology, especially under conditions of abiotic stress such as drought.