In vitro evaluation of fungitoxic potential of different fungicides against Alternaria alternata (Fr.) Keissler causing Alternaria leaf blight of isabgol

Abstract:

Isabgol (Plantago ovata Forsk.) is an important export-oriented medicinal crop of India, which dominates the global market for its seeds and husk. The crop is known to infect by many fungal diseases. Among them, Alternaria leaf blight caused by Alternaria alternata (Fr.) Keissler has become a serious threat for successful isabgol cultivation in Saurashtra. Considering the economic importance of disease, a laboratory experiment was conducted to study the efficacy of different non-systemic fungicides at 1000, 1500 and 2000 ppm; systemic fungicides at 100, 250 and 500 ppm and ready-mixed fungicides at 500, 750 and 1000 ppm concentrations against A. alternata by using Poisoned Food Technique. The results revealed that, among non-systemic fungicides, copper hydroxide 53.8 DF at 2000 and 1500 ppm concentration remained equally effective with mycelial growth inhibition of 92.82 and 92.46 per cent, respectively. In contrast, chlorothalonil 75 WP found less effective at 1000 ppm concentration (57.08%). Among systemic fungicides, propiconazole 25 EC and tebuconazole 25.9 EC each at 100, 250 and 500 ppm concentration gave cent per cent inhibition of mycelial growth of A. alternata. While, thiophanate methyl 70 WP found less effective at 100 ppm concentration (28.60%). Among ready-mixed fungicides, hexaconazole 4 + zineb 68 WP at 500, 750 and 1000 ppm concentration completely inhibited the mycelial growth of A. alternata. While, kresoxim methyl 15 + chlorothalonil 56 WG at 500 ppm concentration found least effective (67.84%) under in vitro condition.