Effect of Fungicides on the Mycelial Growth of Alternaria alternata Causing Leaf Spot Disease in Ashwagandha

A Leaf spot disease was caused by Alternaria alternata ten isolates were collected from the ashwagandha growing different regions of Tamil Nadu. The virulence of the isolates were tested based on the Per cent Disease Index (PDI) and symptom expressed on the foliar surface. The maximum disease intensity of 65.13 PDI was recorded in Chempatti (I₆) isolate. The minimum disease intensity was recorded in I₁₀ from Cumbum (36.83 PDI). Seven fungicides viz., carbendazim(0.05%), mancozeb (0.2%) copper oxy chloride (1%), chlorothalanil (0.2%), fosetyl (0.1%), Ridomil MZ (0.05%) and dithane M 45(0.05%) were tested against A. alternata. Among the fungicides, the minimum diameter of mycelial growth of A. alternata (0.75cm) and maximum percentage of inhibition (91.34%) were recorded in mancozeb (0.2%).