Relative efficacy of various fungicides, chemicals and biochemical against late blight of potato

Four fungicides Antracol, Sancozeb, Dithane M-45, Ridomil Gold, one chemical Sulfur and one biochemical Neem leaf extract were tested on test variety SH-5 during two months seasons 2005-2006 and 2006-2007 for their effect on late blight disease incidence and tuber yield. The field experiment was laid out adopting layout system of RCBD, there replications and 2.8 X 6m plot size. The inoculum of late blight disease collected was applied to the crop thrice for the artificial development of the disease. All the fungicides and chemicals were sprayed to crop at the rate of 2.50 gm/ltr at suitable intervals. Early blight disease was noticed in traces because of unfavourable weather condition in both the years. The averaged data of two years indicated that the fungicide Ridomil Gold effectively controlled the late blight disease showing the least magnitude of the disease incidence as 10.66%. It was followed by the fungicide Dithane M-45 with 10.66% disease attack whereas, the control was found with the maximum disease incidence as 58%. In both the years, significant differences in the late blight incidence were noticed in due to the fungicides as per statistical analysis. However, two fungicides Sancozeb and Antracol, with 16% and 19.16% disease attach promised better control of the disease as compared with Sulfur and Neem leaf extract having 29.16% and 38.66% late blight incidence. All the three fungicides, Ridomil Gold, Dithane M-45 & Antracol spraying resulted in the lowest number of small tubers and greater number of medium and large tubers as compared with the control water spraying. As regards tuber yield, Ridomil Gold fungicide promised maximum tuber yield as 26.27 t/ha followed by Dithane M-45 with 22.90 t/ha potato yield as against control with 13.18 t/ha tuber yield. Both the fungicides Dithane M-45 & Ridomil Gold have almost one and half to two fold tuber yields as compared with control. It was apparent that Ridomil Gold fungicides proved as the most efficacious in terms of 47.33% less blight and 127.94% more tuber yield. It was followed by Dithane M-45 with 43.50% decrease in disease incidence and 98.73% increase in tuber yield.