Fluorescent Dye Paper-Based Method for Assessment of Pesticide Coverage on Leaves and Trees: A Citrus Grove Case Study

Crop disease management depends on efficient and adequate pesticide distribution to reduce pest population. Instrument-based methods to evaluate the spatial distribution of pesticides are available, but they are not field-compatible because of instrument size, cost, and extensive sample preparation. The current gold standard of water-sensitive papers is field-compatible; however, these papers often produce false positives due to reaction with water from sources other than the pesticide mixture. Thus, we developed a novel method in which a fluorescent dye is sprayed over a crop with circles of filter paper (samplers) attached to the leaves. After collection, a lightbox is used to take pictures of the samplers, and an algorithm analyzes each image for percent coverage to visualize the pesticide distribution within the crop. Our method produces results quickly and inexpensively compared to current methods and can be applied to any crop to inform best pesticide application strategies.