Effect of Fungicide Timing on Target Spot

Target Spot caused by Corynespora casiicola is an emerging disease of cotton in the Southeast, and was observed in Tennessee in 2013. Typically disease onset is late in the season, although in certain instances rapid defoliation has occurred.  The relationship of defoliation to yield loss is not well known nor the effect fungicide application has on disease management in Tennessee. The objective of this research is to evaluate the effects of one or two fungicide applications initiated at different timings during bloom on disease severity, defoliation, and yield. Two varieties and 6 to 8 fungicide application treatments (including non-treated check) have been used in a split plot design with 4 replicates in 2014 and 2015 in Jackson, TN. Data recorded includes date of onset of disease, temperature and rainfall, disease incidence and defoliation, machine harvested yields, turn-out, and fiber properties. Results and implications for fungicide application on cotton in Tennessee for management of target spot will be discussed in presentation.