Damping off

Damping off
    This disease was reported in India from Lucknow during the incidence ranged from 40-60 %.
    Symptoms
    • Pre-emergence& post-emergence damping off occurs in opium. Severely affected seedlings show decay of root and collar region.
    • Diseased seedlings die in 3-5days after attack.
    • Mycelium of fungus is white and coenocytic, sporangia are filamentous, slightly inflated with discharged tubes.
    • Oogonia may be terminal or intercalary, spherical and 19-24 micrometer in diameter. Antheridia 1-3 micrometer
    • Oospores are single, plerotic, 17-20 micro meter in size with 1.3micrometer thick walls.
    Etiology
    • Pythium dissotocum Drechsle.
    • Mycelia: Aseptate, Asexual spore- Zoospore, Sexual spore- Oospores borne in oogonium
    • MODE OF SPREAD AND SURVIVAL:
    • Primary source of inoculum : Oospores, affected debries.
    • Secondary source of inoculum: Zoospores
    Epidemiology
    • Temparature: 22-24oC
    • High relative humidity: 90 %,
    • High density seedlings
    • Low lying areas
    • Increased moisture-80-90 %
    • Susceptible host.
    Management
    • Raised methods for sowing, Line sowing with proper spacing,
    • Soil sterilization with 4 % formaldehyde upto depth of 30 cm,
    • Seed treatment with captan -2g /kg or Mancozeb-2g /kg of seed.

Last modified: Thursday, 1 March 2012, 1:40 PM