This abstract and presentation provides information on how to recognize sugarcane orange rust, its distribution and status in Florida and the Central America and Florida’s response to control this emerging disease.

Technical Abstract: Symptoms consistent with sugarcane orange rust were first observed in Florida in June 2007, these were subsequently confirmed morphologically and molecularly as being caused by Puccinia kuehnii, the causal agent of orange rust. This was the first documented occurrence of sugarcane orange rust in the Western Hemisphere. Since then it has been reported in Guatemala, Costa Rica and Nicaragua and has been confirmed in several other Central American and Caribbean Countries. A comparison of brown rust and its causal agent, Puccinia melanocephala and P. kuehnii, will be presented. Orange rust has impacted both the commercial production and the cultivar development program in Florida. One major difference in the epidemiology of the two pathogens is that P. kuehnii tolerates warmer temperatures and orange rust severity continues throughout the summer and early fall lasting much longer than brown rust. This is significant as it means that commercial cultivars susceptible to both pathogens are impacted throughout the growing season. A cultivar that occupies 25 % of the acreage in Florida, CP 80-1743, is susceptible to the disease and has had reduced cane yields. It is being withdrawn from production. Results from a comprehensive approach towards developing sugarcane cultivars resistant to orange rust that is being adopted in the Canal Point breeding program will be presented. This involves identifying and discarding susceptible sugarcane clones as early in the breeding program as possible, the development of novel screening methods and the identification of sources of resistance for breeding.