Abstract

Assessment and identification of diseases on sugar cane accessions in the germplasmof national cereals research institute, Badeggi, Nigeria

Author(s): A.C.Wada,M.S.Bassey, B.O.Ehirim

A studywas carried out at the National Cereals Research Institute, Badeggi (lat. 9o045’N; long 6007’E at an altitude of 70.57m above sea level) for the assessment and identification of diseases on some sugar cane accessions in the National germplasm maintained at the institute and research plots of scientists in 2013. The cane fields were surveyed using random field checking technique. Ten leaf samples with mixed infections were cut from the national germplasm, the CFC-WASDP multiplication field, the introductions from Brazil and experimental plots of researchers. The cut samples were taken to the microbiology unit of Central Services Laboratory of the institute for isolation and characterization. The samples were placed in running tap water to remove sand and debris. They were then soaked in distilled water with addition of sodium hypochlorite for 3-5 minutes and were rinsed 3 to 5 times with distilled water. With a sterilized surgical blade, samples were cut from the junction of lesions and healthy regions and plated on Potato dextrose agar (PDA) prepared in a ratio of 200:20:15 g/litre at a PH of 5.6±0.2. and incubated at 30-35oC for 2-5 days. Germinating spores were sub cultured and brought to pure culture and then mounted in glass slides with lactophenol blue solution at a magnification range of ×10 - ×100. Four of the isolated pathogens were identified to species level based on the characteristic colonies produced on PDA and spore morphology in the case of whip smut which was not cultured as it does not grow on axenic media with reference to relevant texts. Pathogens were identified at different percentage infection rates from both local and exotic cane accessions. Results showed that one was of bacterial origin (Xanthomonas axonopodis), and four of fungal origin namely Sporisorium scitamineum Syd., Colletotricum falcatum, Paraphaeosphaeria michotii and Puccinia melanocephala.