Comparison of serological diagnostic tests for the detection of Clavibacter xyli subsp. xyli, the causal bacterium of ratoon stunting disease in sugarcane

Ratoon stunting disease (RSD), caused by the bacterium Clavibacter xyli subsp. xyli, is well established in most sugarcane growing regions of the world (Gillaspie and Teakle, 1989) and is considered to be the disease causing more yield losses worldwide than any other sugarcane disease (Hughes, 1974). In order to improve RSD diagnosis, serological techniques ahve been developed to screen sugarcane for the presence of the causal bacterium. Davis and Harrison (1988) developed an indirect dot-blot enzyme immunoassay (IDB-EIA) technique to enumerate the RSD-associated bacteria deposited onto nitrocellulose membranes. Screening for RSD using an indirect (Harris and Gillaspie, 1978) and a direct (Davis 1985; Davis and Dean, 1984) fluorescent antibody labelling procedure has also been tried. Both methods were found to be more sensitive than PCM.