Leaf blight of banana and its control
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Date
1993
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Department of Plant Pathology, College of Agriculture, Vellayani
Abstract
Survey conducted to study the fungal pathogens causing leaf blight disease in banana in the three agricultural subdivisions of Thiruvananthapuram district, yielded seven fungal pathogens viz., colletotrichum musae, Curvularia sp, Guignardia musae, khuskia oryzae, Nodulisporium gregarium, Pestalotiopsis versicolor and Phaeoseptoria sp. Among these, Curvularia sp, Khuskia oryzae and Nodulisporium gregarium are new reports.
Morphological characters and pathogenicity tests of all the seven isolated cultures were studied and described. Detailed studies were conducted on five fungal pathogens viz., C. musae, G. musae, K. oryzae, N. gregarium and Phaeoseptoria sp., since severe infections could be noticed by these fungi.
Studies conducted on the growth and sporulation of pathogens on different, media indicated that Richard’s medium was the best for C. musae and G. musae, potato dextrose medium for K. oryzae and Phaeoseptoria sp. In the case of N. gregarium, potato dextrose agar and Czapek (Dox) broth were found to be the best solid and liquid media respectively for its growth.
Best growth of C. musae, N. gregarium and Phaeoseptoria sp was obtained with maltose as the carbon source, whereas G. musae and K. oryzae utilized maximum starch and sucrose for their growth. Maximum mycelial weight of C. musae was obtained with sodium nitrate as nitrogen source, G. musae and K. oryzae with potassium nitrate, N. gregarium with glutamine and Phaeoseptoria sp. with asparagine.
Potato dextrose broth and Richard’s solution were found to be best media for the toxin production by C. musae K. oryzae , G. musae and Phaeoseptoria sp. produced maximum toxin in Richard’s solution and N. gregarium in potato dextrose broth.
Host range studies of the pathogen (s) conducted indicated that they can infect a number of economically important plants like, clove, cocoa, colocasia, nutmeg and tapioca, but none of the pathogens could infect clerodendron.
Dithane M-45, calixin and Bavistin were able to inhibit the growth of the leaf blighting pathogens under laboratory conditions and under field conditions Dithane M-45 (0.2%) was found to be the best.
Varietal screening trials showed that variety Rasakadali was moderately resistant/tolerant among the four popular varieties screened, whereas Nendran was the most susceptible variety.
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170487