Effect of host nutrition on the development of Colocasia blight

Effect of different nitrogenous fertilizers on the severity of Colocasia blight caused by Phytophthora colocasiae Rac., and yield of Colocasia was assessed under field conditions during 2003 and 2004. Different nitrogenous fertilizers (urea, CAN and Ammonium Sulphate) increased disease severity but yields were also increased. Maximum disease severity was observed with urea and as the dose of N fertilizers (N₆₀ - N₁₂₀ kg/ha) was increased, an increasing trend in disease severity was observed. Maximum disease severity of 45.9 per cent was recorded at N₁₂₀ kg/ha with the yield of 5.8 t/ha. However, with the increasing dose of phosphatic (P₃₀ – P₇₅ kg/ha) and potassic (K₃₀ – K₆₀ kg/ha) fertilizers, a decreasing trend in disease severity was noticed. The disease severity and crop yields increased as the dose of IFFCO increased and maximum yield of 5.2 t/ha was realized at NPK (12:32:16) @ 247.5 kg/ha.