The particle film is designed to allow photosynthetically active radiation through, while blocking or reflecting harmful radiation that can cause sunburn and heat stress. Surround treatments keep the foliage and fruit cooler and can reduce heat stress and improve fruit color, stated Mosko. Relief from heat stress can lead to larger fruit size under certain conditions. When sprayed on plant surfaces, the protective barrier creates an unfamiliar and hostile environment to pests. Also, particles adhere to the insect or mite and act as a strong irritant, causing them to abandon the treated surface.
Some pests have difficulty gripping the loosely bound particles and fall from the plant surface.
Prolonged exposure to the film increases particle attachment to the insects, leading to confusion, disorientation, and excessive grooming, Mosko explained. Data are still being collected on Surround's effect on beneficials and parasites. Lady beetles and green lacewings appear to operate well against aphids in particle film-treated apple orchards, he said, adding that honeybees and other pollinators do not appear to be affected by the particle films. Particle film products are made up of ingredients with low mammalian toxicity and minimal environmental risks. The reentry interval established by the EPA is expected to be four hours from time of application, with a preharvest interval requirement of ten days.