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Evaluation of sugarcane clones in the CP-Cultivar Program for resistance to puccinia kuehnii, the pathogen of orange rust
- S. Sood, J. C. Comstock, R. N. Raid
- Proceedings of the International Society of Sugar Cane Technologists 2013 v.28 pp. 1-7
- Puccinia, Saccharum, clones, cultivars, disease resistance, environmental factors, genotype, germplasm evaluation, inoculation methods, inoculum, leaf area, orange rust, pathogens, sporulation, sugarcane, Florida
- 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.