Management of Leaf Spot of Aloe barbadensis (Mill.) caused by Alternaria Alternata (Fr.) Keissler with fungicides and bio agents.

Abstract

Among the several diseases, leaf spot disease is one of the most destructive foliar disease which causes heavy loss in Aloe vera. Isolation, morphological studies and pathogenicity tests revealed Alternaria alternata (Fr.) Keissler as causal organism. Among the four culture media, the best growth of the fungus was obtained on malt extract agar medium followed by potato dextrose agar medium. Out of seven different fungicides tested in vitro, Tebuconazole, Myclobutanil and Hexaconazole at all the concentrations (0.05%, 0.1% and 0.2%) completely inhibited the mycelial growth of A. altemata. Among the nine bio-control agents tested against A. alternata under laboratory condition in dual culture, Trichoderma koningii recorded highest inhibition of radial growth. T. harzianum, T. atraviride, and T. viride were next in order. In case of field evaluation of fungicides and bioagent T. koningii effectively managed the disease followed by T ebuconazole and T. harzianum.