Monitoring the health of Huanglongbing-affected citrus trees by following changes in leaf Candidatus Liberibacter asiaticus (CLas) titer has an inherent element of imprecision because CLas titer varies considerably within the tree canopy and with calendar seasons. In addition, the destructive sampling method used to determine CLas titer entails a different set of leaves per sampling period adding to the inconsistency and inexactitude of the results. To overcome these ambiguities and to reduce the numerical variability between samples, we developed an experimental method that analyzes portions of the same treated leaves for up to four sampling periods. By assaying subsamples of adjacent locations of the same leaf, random variability was significantly reduced, and comparative analysis can be carried out with greater precision.
Ed Etxeberria, Pedro Gonzalez, Ariel Singerman and Timothy Ebert
Franklin R. Hall, Roger A. Downer, Jane A. Cooper, Timothy A. Ebert and David C. Ferree
Apple (Malus domestica Borkh.) leaves were sprayed to runoff using a selection of pesticides, and subsequent spray retention was evaluated by weight. Timing, cultivar, leaf surface, and leaf type significantly influenced spray retention. Spray retention correlated significantly and positively with leaf hair density. The importance of these differences is considered in relation to the possible efficiency of the pesticide application process in apple orchards.