Comparison of phase contrast and fluorescence microscopy for assessment of ratoon stunting disease infection in sugarcane

Ratoon stunting disease (RSD), caused by the bacterium Clavibacter xyli subsp. xyli is acknowledged to be present in most canegrowing countries (Anon., 1989). It is regarded as the most important disease affecting sugarcane production (Hughes, 1974; 1978) and it persists in all canegrowing areas in Australia, despite costly efforts to control it. For assessment of clonal resistance to RSD to be used in selection and breeding of resistant clones, rapid and reliable quantitative measures of infection are required.