Kenneth Gravois | 4/5/2005 11:32:05 PM
Ratoon stunting disease, better known as RSD, has been the most damaging disease of sugarcane for many years. RSD is spread during planting and on equipment during harvest. It has no visible, external symptoms, except for stunted growth. This means farmers do not know when they have RSD or when they are spreading it.
RSD is controlled by planting healthy seedcane and making sure the disease is not introduced later. Healthy seedcane used to be obtained by heat-treating stalks to be used for planting. This was inconvenient, did not provide complete control and sometimes damaged the stalks. Therefore, heat treatment was never fully used by the industry and RSD was not effectively controlled, even though sugarcane cultivars could sustain up to 50% loss in yield.
During the last 15 years an alternative program has been developed through a partnership between the LSU Ag Center and a private company using tissue culture, or micropropagation, to produce healthy seedcane for farmers. The Louisiana Agricultural Experiment Station (LAES) was involved in initial evaluations of "Kleentek*" seedcane. LAES, USDA, industry and Kleentek representatives then developed regulations to provide quality assurance that certain standards would be met during seedcane production. This "certification" is the responsibility of the Louisiana Department of Agriculture and Forestry.
In 1995, a lab for micropropagation of sugarcane was donated to the LSU AgCenter to be operated by Kleentek personnel. LAES has conducted a "local quarantine" since 1998 to ensure that micropropagation begins with healthy plant material, and the LAES Sugarcane Disease Detection Lab was established in 1997 to provide an independent assessment of the RSD status of Kleentek seedcane and to monitor RSD in farmers' fields. In addition, sugarcane varieties were evaluated for resistance to spread of RSD.
RSD testing for sugarcane farmers has provided an annual survey of the industry that documents a steady decrease in the occurrence of this most important disease. A 1984 survey found that 22% of all stalks tested had RSD. In the first three years of operation by the Sugarcane Disease Detection Lab, the frequencies of stalk infection were 12%, 3% and 2%. The factors associated with decreasing RSD frequency are increasing use of Kleentek seedcane and increased cultivation of a high-yielding variety, LCP 85-384, that is resistant to RSD spread.
LCP 85-384 was developed through another public and private sector partnership, the Louisiana Sugarcane Breeding Program that is cooperative among the LSU AgCenter, the USDA Sugarcane Research Unit and the American Sugar Cane League. Because of this partnership and the working relationships developed among the LSU AgCenter, Kleentek, and the Louisiana Department of Agriculture and Forestry, it appears that we are winning the war against RSD. This is a major accomplishment for the Louisiana sugarcane industry.
State and Hatch Act funds, the American Sugar Cane League, Kleentek