Incidence of malformation in mango (Mangifera indica) nurseries in eastern Uttar Pradesh.
Gaur V. P., Chakrabarti D. K.
Author Affiliation: Narendra Deva University of Agriculture and Technology, Faizabad, Uttar Pradesh 224 229, India.
Indian Journal of Agricultural Sciences 79 : 160-162
Abstract : In a survey conducted in mango nurseries in eastern Uttar Pradesh on incidence of malformation (bunchy top) caused by Fusarium mangiferae on 7-month-old seedlings and grafted saplings of mango of different cultivars, percentage of malformed seedlings was recorded 0.70-4.25 while on grafted saplings 0.5-67.3. Grafted saplings of regular bearing cultivars (Amrapali, Mallika, Baramasi) showed more infection than the alternate bearers (Dashehari, Langra, Chausa). The nurseries under shade and inside malformed mango orchards had higher disease incidence while less in poly house at 25-31°C. The disease development was promoted by high rainfall but affected by high temperature and bright sunlight. The malformed seedlings initially were taller than the healthy ones. But after development of bunchy top at its apex, the elongation was arrested. Of the fungicides tested, captan was most effective in arresting mycelial growth, followed by carbendazim. Mangiferin Cu++ chelate initially stimulated mycelial growth but later caused complete lysis of the hyphae. All the compounds reduced the fungal infection on the emerging vegetative buds. Captan was most efficacious. Captan and mangiferin Cu++ chelate increased mangiferin (anti-fusarial phenolic compound) accumulation in host cells and population of Aspergillus niger (a natural antagonist) on host surface. In a field trial also the best results in terms of successful grafting, development of healthy scions with luxurious growth were obtained with captan.