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Title: Evaluation of sugarcane clones in the CP-Cultivar Program for resistance to puccinia kuehnii, the pathogen of orange rust

item Sood, Sushma
item Comstock, Jack
item RAID, R - University Of Florida

Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2013
Publication Date: 6/25/2013
Citation: Sood, S.G., Comstock, J.C., Raid, R.N. 2013. EVALUATION OF SUGARCANE CLONES IN THE CP-CULTIVAR PROGRAM FOR RESISTANCE TO PUCCINIA KUEHNII, THE PATHOGEN OF ORANGE RUST. International Society of Sugar Cane Technologists Proceedings. 28:1-7.

Interpretive Summary: An artificial inoculation procedure to determine the disease reaction of sugarcane genotypes to orange rust is described. Ratings obtained are similar to those obtained based on natural infection without as many disease escapes. Thus, the method is more reliable and will benefit the sugarcane selection program at Canal Point to develop resistant high yielding sugarcane cultivars.

Technical Abstract: Since the detection of sugarcane orange rust in Florida in 2007, there has been a program to identify resistant clones in the Canal Point (CP) Cultivar Development Program. Both natural infection and artificial inoculations techniques have been used. Although natural infection requires less labor, results are dependent on the availability of natural inoculum and the conduciveness of environmental conditions. A whorl inoculation method initially developed for brown rust has now been used annually for approximately 1700 clones that are in yield trials (Stages II through IV) in the CP Cultivar Development Program. Symptoms are rated using two different systems. Natural infection is rated using the rust severity level (percentage of leaf area affected), while whorl inoculated plants are rated on the presence and level of pathogen sporulation. The two methods have demonstrated good agreement (correlations, r2 = 0.72-0.95), although higher numbers of genotypes are rated susceptible by the whorl inoculation technique. There has been progress in developing orange rust resistance and this will be discussed.