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Subject: Plant Pathology × Author: Abhijeet Shankar Kashyap × End date: 2013 × Start date: 2013 × Type: Thesis ×
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    ThesisItemOpen Access
    Studies on Leaf spot of Tomato Caused by Septoria lycopersici speg.
    (UAS, Dharwad, 2013) Abhijeet Shankar Kashyap; S. Lingaraju
    Tomato (Solanum lycopersicum L) regarded as poor man’s apple, is one of the widely grown and most popular vegetable crops belonging to family solanaceae. Septoria leaf spot (Septoria lycopersici Speg.) is one of the most devastating foliar diseases in humid regions, particularly during the periods of rainfall, incurring loss both at pre and post-harvest stages in tomato. The isolated fungus grown on potato dextrose agar produced dull white mycelium conidia were hyaline, flexuous and filiform with 1-9 septations. The conidia measured 30.30 to 75.00 μm in length and 2.2 to 3.0 μm in breadth. Successful pathogenicity of the fungus on tomato was proved following Koch’s postulates by inoculating using the spore suspension. Cultural studies revealed that among solid media, potato dextrose agar and tomato leaf extract agar were found to be good for growth of S. lycopersici. Among the liquid media, Potato dextrose broth and Tomato leaf extract broth supported maximum dry mycelial weight of fungus on 13th day of incubation. Physiological studies revealed that optimum pH range of 6 to 7 was favourable for growth and sporulation of pathogen. Maximum dry mycelial weight was obtained in temperature range of 20 to 25ºC. Alternate cycles of 12 hours light and 12 hours darkness favoured the maximum radial growth and dry mycelial weight of S. lycopersici. Tomato variety L-15 was found to be resistant against Septoria leaf spot under glasshouse conditions. Among the ten fungicides evaluated in vitro against S. lycopersici, Hexaconazole, Propiconazole and Carboxin + Thiram gave total inhibition of the fungal growth at all concentrations. Among antagonists tested in vitro, Trichoderma harzianum gave maximum inhibition of mycelial growth. Effective field management of the disease was obtained by Azoxystrobin with B:C ratio of 4.71:1.