Efficacy of plant extracts, biological agents and fungicides against Alternaria alternata incited leaf spot and fruit rot of papaya

Leaf spot and fruit rot of papaya are important fungal diseases caused by Alternaria alternata (Fr.) Keissler causes heavy losses in Gujarat. The extract of garlic bulb (Allium sativum) at 15 per cent concentration showed maximum growth inhibition of A. alternata (88.91%) which was at par with Lantana leaves (88.35%) and dhatura leaves (87.51%). Both the species of Trichoderma inhibited the growth of A. alternata. However, T. viridi (S.K. Nagar) showed significantly maximum per cent growth inhibition (91.95%). The systemic fungicide propiconazole at 1000 ppm showed significantly maximum growth inhibition (98.05%). Out of non-systemic fungicides, mancozeb (1000, 1500, 2000 and 2500 ppm) showed complete growth inhibition of the fungus at lowest concentration. Among combined fungicides, metalaxyl + mancozeb (ridomil-MZ) at 1000, 1500 and 2000 ppm concentration showed complete growth inhibition of the fungus. Minimum leaf spot and fruit rot intensity (13.93 and 12.90%) was seen in spraying of mancozeb @ 0.2%.