Status of ratoon stunting disease of sugarcane (Leifsonia xyli subsp. xyli) in Nigeria

Leifsonia xyli subsp. xyli ( Lxx ), the causal agent of ratoon stunting disease of sugarcane (RSD), is a major constraint to sugarcane production worldwide. In Nigeria, the presence of RSD has not been conclusively determined. This study investigated the presence or absence of RSD through surveys in 18 sugarcane growing states in Nigeria. Sugarcane plants or ratoon crops of 7–12 months of age were randomly sampled, and a total of 1190 samples of sugarcane stem cuttings from 76 cultivars were collected. The lowest four internodes were cut longitudinally into nodes, and examined internally for reddish comma-like discoloration. PCR was conducted on DNA extracted from sugarcane sap using Lxx -specific primers. Reddish comma-like internal symptoms of RSD were observed only in samples of cultivar Co510. None of the sugarcane samples, including those from Co510, yielded the 438 bp band expected for PCR detection of Lxx . Immunofluorescence microscopy analyses performed at SASRI, South Africa, using sap from the collected sugarcane samples, also did not detect the bacterium. Thus, the presence of RSD of sugarcane in Nigeria was not confirmed, contrary to its reported presence in 1956. Strict quarantine procedures should be followed to prevent introduction of the pathogen into Nigeria.