Studies On Leaf Spot Disease and Screening for Clonal Resistance in Nothapodytes nimmoniana: an Anti-Cancer Drug Yielding Tree
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Date
2017-06
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University of Agricultural Science, Dharwad
Abstract
Nothapodytes nimmoniana is one of high camptothecin (CPT) yielding tree. Though the incidence of fungal leaf spot disease has been reported, except the recordance of the disease there was no systematic work carried out on various aspects of the leaf spot disease of N. nimmoniana. The pathogen associated with the leaf spot disease of N. nimmoniana was isolated and identified as Cylindrosporium mappiae. To prove its pathogenicity different inoculation methods were followed, among all the methods swabbing, brushing, sticking above surface and sticking below surface methods were proved to be effective in symptom expression.
For the first time screening of the forty four clones of N. nimmoniana against leaf spot disease was carried out in the clonal orchard of College of Forestry, Sirsi during 2015 and 2016. The clones Px and O from Pune and Mahabaleshwara respectively were moderately resistant to Cylindrosporium leaf spot disease. After two years of screening it was found that two clones were moderately resistant, 7 clones were susceptible and 35 clones were highly susceptible to Cylindrosporium leaf spot disease. Biochemical contents viz. reducing sugars and phenols was estimated in all the clones. The strong association between disease and estimated biochemical contents in the clones was recorded.
The management of the disease was carried out under both in vitro and in vivo conditions. Among the different fungitoxicants used Trichoderma harzianum IOF strain has recorded growth inhibition of 99.81 per cent, Azadiractha indica (98.40%), Tebuconazole 250 EC (99.63%), Trifloxistrobin 25% + Tebuconazole 50%, 75% WC (100%), Hexaconazole 4% + Zineb 68%, 72% WP (96.30%) and Hexaconazole 5% + Captan 70%, 75% WP (98.92%) were found effective under in vitro conditions. Similarly, the combi product Trifloxistrobin 25% + Tebuconazole 50%, 75% WP has recorded the lowest disease index of 44.23 per cent and found effective under in vivo conditions.