Rakesh Yonzone2017-02-202017-02-202012http://krishikosh.egranth.ac.in/handle/1/5810001637Red stripe/ Top rot disease of sugarcane, caused by a bacterium, has been observed to be quite severe on variety CoJ 85 during the past 4-5 years in Punjab. Survey was conducted June-August 2011and it was found that the maximum prevalence of Red stripe (21.1%) and Top rot (40.4%) phase was recorded on variety CoJ 85 in Amritsar district and the minimum prevalence 1.6 per cent and 3.5 per cent respectively, on variety CoJ 88. Highest disease severity, 39.0 per cent of Red Stripe phase in the month of July was recorded on the variety CoJ 85 and lowest severity 5.0 per cent in July was observed on variety CoJ 88. Highest disease severity (5%) of Top rot phase in month June was recorded on variety CoH 119 and 65.8 per cent in months of August was recorded on the variety CoJ 85. The maximum growth of the pathogen was observed on King’s B media after 24 hrs followed by YDCA media after 46 hrs of inoculation. The three isolates viz., RS-2, RS-3 and RS-8 were found to have higher disease intensity (57%) and stripe length (30 cm). Regarding, morphological characteristics, the isolates were found to be gram negative, short rods with rounded end, 1.5-2.0×0.4-0.8 µm in size, yellow colour and circular type colony. All the ten isolates showed negative results in urease utilization and phenylalanine and positive results in citrate, sorbitol, lysine, ornithine utilization and H2S production. The isolates were also found to be aerobic and non-fluorescent. Molecular identification revealed that the pathogen associated to the Red stripe disease in Punjab State is Acidovorax avenae sub sp. avenae. Bud inoculation with pin prick method proved to be the best followed by hypodermic syringe method. In epidemiological studies, the maximum lesion length 32.28 cm was recorded on variety CoJ 85 followed by 27.72 cm in CoJ 88 after 32 days of inoculation.ennullThesis