September 2015 The objectives of this proposal are 1) Determine the base line level of Guignardia citricarpa sensitivity to fungicides registered for disease control in citrus and evaluate new products for efficacy against G. citricarpa in vitro; 2) Conduct and improve implementation of spray trials for efficacy of registered products for citrus and to evaluate novel compounds in the field; 3) Optimize field evaluation of control measures through analysis of the spatiotemporal disease progress utilizing past and current field data of the outbreaks to gain knowledge on the incidence, severity and rate of the epidemic and assess the fungal population to increase the likelihood of successful field research and 4) Evaluate products and treatment conditions for postharvest control of citrus black spot. This quarter we accomplished: Objective 1: Manuscript preparation continues for the DMI fungicides. Media were selected for experiments with SDHIs and the assays with Endura are nearly complete. Other SDHIs are underway. Experiments with Cannonball and Vanguard are continuing. The mycelial tests are complete and spore germination assays are still on-going. Objective 2: Fungicide trials were initiated in 2015. Since July 2 applications were made for the fungicide trial. The disease is in its latent phase. Objective 3: We are waiting for the disease to start expressing for data collection Objective 4: It was found that Eugenol volatiles alone, whether 50 �L/L or 100 �L/L, did not inhibit mycelial growth of any of the three Guignardia citricarpa isolates tested, but it did decrease the number of conidia formed on colonies for all three isolates and in a dose-dependent manner (P < 0.05). After 14 day incubation, exposure to 50 �L/L of eugenol volatile decreased the number of conidia from isolates CNGC, PPST, or GC1 by 79%, 54%, or 79%, respectively, and exposure to 100 �L/L of eugenol volatiles decreased the number of conidia of the above three isolates by 90%, 74%, or 78%, respectively, compared to the control.