Keeping Cool with Particle Films
Posted August 2025
Researchers: Christopher Vincent
Contact: Christopher Vincent, UF/IFAS CREC civince@ufl.edu
Summary:
Particle films have long been used to repel insect pests and enhance tree growth. Particle films are simply suspensions of solid particles that form a film over the surface of the leaf after they are sprayed and dried. They repel insects by reflecting different colors of light that keep the insect from identifying its host. They improve plant growth by dispersing light more evenly allowing leaves to stay cool and stomata to stay open for photosynthesis. Our research confirms that particle films can reduce psyllid pressure, delay huanglongbing (HLB) infection, and enhance growth in young trees. Dyeing the natural white color with red, improved psyllid control and moderately improved citrus growth over the white. The result was that by year three of a planting, particle film-treated trees produced three times greater yields than trees treated with foliar insecticides at least once per month. In the same year, fruit from particle film treated trees had 1 °Brix more than control trees. With detailed studies we saw that particle films improve leaf water status even when trees have enough soil water and that they reduce heat stress by keeping leaves about 10° cooler in the summer. We have found, though that in cooler weather (<70 °F) particle films can reduce photosynthesis, and high rates of particle films provide too much shading. While in moderate weather, low rates of particle films can improve water status, and in high summer temperatures higher rates are helpful. We are currently researching what rates are best for growth and yield. The best results we have obtained in bearing trees are with 12.5 lb per acre of Surround® WP, about 1/2 the labeled rate. We can retain the product on the tree by mixing it with a carnauba wax product. For now, we can conclude that particle films reduce Asian citrus psyllid (ACP) pressure; delay HLB infection; increase growth and yield, by reducing stress and improving tree water status; and the best choice of red versus white and rates may depend on the season.
Take Home Message:
- Particle films increase growth by shading trees.
- Particle films are most beneficial in spring, summer, and fall, and probably not in winter.
- Rates of approximately 1/2 the labeled rate (12.5 lb/acre) are likely to be the most effective, and reapplication can be limited by including a carnauba wax product.
