Effect of Soil Amendments with Organic and Inorganic Manures on the Incidence of Dry Root Rot of Groundnut

Field experiments were conducted at Regional Agricultural Research Station, Tirupati on sandy loamy soils to determine whether soil amendment with organic (Farm Yard Manure) and inorganic manures (N, P, K, Gypsum, Lime and Zinc sulphate) affect the severity of dry root rot in groundnut (Arachis hypogaea L.) caused by Macrophomina phaseolina (Tassi) Goid. Farm Yard Manure, nitrogen, phosphorus, potassium, gypsum (calcium sulphate), lime (calcium hydroxide) and Zinc (Zinc sulphate) were evaluated alone and/or in various combinations. Combined doses of inorganic manures (20 Kg N + 10 Kg P + 25 Kg + 250 Kg Gypsum + 25 Kg Zinc sulphate (once in three years) proved best out of all treatments tried. It reduced dry root incidence (31.64%) and gave the highest pod yield (20.42 q/ha). Farm Yard Manure applied at 5 tonnes/ha, once in three years was found nearly as effective as the above treatment in reducing the dry root rot to 32.28% and increasing the yield upto 20.42 Q/ha. Nitrogen at 20 kg/ha has reduced the disease incidence significantly over the control. However it has failed to increase the pod yield significantly over the control. The other treatments, 10 kg P and 25 Kg K individually were found ineffective in reducing the disease incidence and increasing the yield. However the combination of N P K was.found to be effective in controlling the disease and increasing yield.