Film-Forming Sprays on Citrus in Florida

Abstract

During recent years, chemists, entomologists and plant pathologists have developed effective pesticides from practically all known types of toxic chemicals in both organic and inorganic groups. However, there have been few attempts to determine the value of non-toxic physical barriers applied as coatings for plant protection. The possibility of using materials that are low in toxicity to people as well as insects is especially interesting at this time, when public health authorities are introducing increasingly strenuous controls against the use of highly toxic materials on crops. The purpose of this study was to determine whether a mechanical film would protect citrus plants from citrus rust mite, Phyllocoptruta oleivora (Ashm.), and greasy spot disease. Since 1955 various plastic, synthetic latex and wax materials, commonly used in industry for paints, binders and water-resistant coatings, have been applied as sprays to determine filming characteristics and effects on citrus plants. Formulations were non-toxic milky-white, aqueous emulsions containing about 50 percent solids. Other characteristics were a particle size of less than 1 micron, a specific gravity of about 1 and pH ranging from less than 3 to more than 9. All of the materials tested mixed with water in all proportions and dried to solid films that would not go back into suspension upon subsequent wetting with water.