Variation in Sensitivity to Fungicides among Isolates of Alternaria solani Causing Tomato Leaf Blight Disease

Abstract

Isolates of Alternaria solani causing tomato leaf blight disease were collected from twenty conventional tomato growing regions and their pathogenicity established. A wide variation existed among the isolates in terms of virulence on tomato plants. Sensitivity of the isolates to different fungicides was evaluated based on mycelial growth on fungicide-amended culture media and spore germination after fungicide treatment. All the chemicals tested were effective in reducing the mycelial growth and spore germination of A. solani isolates however, mancozeb (0.2%) followed by captofol (0.2%) were more effective. Virulent isolate recorded more mycelial growth and spore germination. A positive correlation was found between the virulence of isolates and ability to grow and sporulate after exposure to fungicides.