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Poster: Epidemiology: Analytical & Theoretical Plant Pathology


Identification of conducive temperatures for decision support modeling of sugarcane rusts in Florida
B. CHAULAGAIN (1), M. Hincapie (1), S. Sanjel (1), C. Fraisse (2), R. Raid (1), P. Rott (1) (1) University of Florida, U.S.A.; (2) University of Florida, U.S.A.

Most sugarcane varieties grown in Florida are currently susceptible to either brown (Puccinia melanocephala) or orange (Puccinia kuehnii) rust, two diseases that have been reported to cause economic losses in sugarcane industries worldwide. In Florida, sugarcane rusts are controlled using fungicides and application schedules are solely based on disease scouting. In order to develop a forecasting system to optimize fungicide applications, disease severity data were collected during the entire 2014 crop season. Percent rust affected area of the top visible dewlap leaf was recorded every two weeks from seven sugarcane varieties susceptible to brown or orange rust and planted in October, November and December 2013. Brown and orange rust progress curves were generated using maximum disease severity values at each scoring date, whatever variety and planting date. Because relative humidity and leaf wetness does not appear to be a limiting factor for development of sugarcane rusts in Florida, efforts were focused on temperature that is also known to affect rust progress. Curves of cumulative average daily temperatures between 170C and 290C were compared with disease progress curves. Temperature ranges of 17-25.50C and 17-26.50C appeared to be the best fit for progress of brown and orange rust, respectively. Weather and disease data from additional crop seasons need to be analyzed to confirm these first results and to develop a decision support model for rusts in Florida.