Varietal control of ratoon stunting disease (RSD) of sugarcane
Ratoon stunting disease, caused by the xylem-limited bacterium Clavibacter xyli subsp. xyli, is prevalent in most sugarcane-producing countries, including Australia. It is regarded as the most damaging disease of sugarcane and under unfavourable conditions, principally drought stress, yield of intolerant cultivars may be reduced by 50%. Control of RSD has been hindered by the fact that it produces no obvious symptoms. Recommended control measures of heat therapy and farm hygiene have failed to adequately control the disease and it remains present at high levels in a number of countries where such control has been attempted for many years. Genetic variation for RSD susceptibility has been recognised since discovery of the disease in 1950 and work towards genetic control of RSD ,•/as begun at Macknace with CSR funding in 1986. When SRDC funding for the work was sought in January, 1988, the stated Objectives were:- 1. To develop pot-testing procedures to reliably and economically rate varieties for RSD resistance. 2. To rate existing commercial varieties for RSD resistance so that growers may manage them more effectively. 3. To select varieties with improved RSD resistance from existing seedling populations. 4. To eventually breed specifically for improved RSD resistance.