Damping off is a major threat to raising healthy onion seedlings during Khariff season in all onion growing areas of the country. Generally 20-25 per cent onion seedlings get damaged due to this disease especially in nursery.
It is caused by soil borne fungal pathogens. Heavy summer showers cause huge mortality in the crop. Integrated approach is an effective and sustainable tool for the management of damping off disease in onion nursery.
Farmers are advised to grow Agrifound Dark Red, Arka Kalyan, N-53, Baswant-780, Bheema Raj and Bheema Red for north Indian regions and Agrifound Red, Co-1, Co-2, Co-3, Co-4 and Co-On-5 are suitable for Southern areas.
Integrated methodsRaised beds should be prepared for raising onion nursery (15-20 cm above at the soil surface) during Kharif.
Soil solarization by covering the nursery beds with transparent polythene for 25-30 days during May and June months is effective to prevent this infestation spread.
Soil treatment with fungal bio-agents like Trichoderma viride/T.harzianum at 5 kg/ha mixed with of well rotten FYM or vermicompost in nursery bed is advised.
Application of vermicompost at 2.0 tonnes/ha in nursery beds. Seed treatment with fungal bio-agent T. viride at 5g/kg seed or Thiram at 2.5g/kg seed is advised.
Use 8-10 kg seed to raise nursery for planting in one hectare area is sufficient.
The treated seeds should be sown by broadcasting method or in lines at a distance of 7-10 cm on the raised beds.
Avoid sowing of thick seed in nursery beds. Use the shade net to protect the nursery from heavy rains.
Irrigation should be done at regular intervals to maintain the optimum moisture in nursery beds.
When symptoms of damping off disease are visible, the drenching should be done immediately with Bavistin at 0.1 per cent or Thiram at 0.25 per cent in onion nursery to control the damping off.
(Dr. R. K. Singh, Assistant Director, Horticulture, NHRDF, Nashik, email: singhrknbpgr@yahoo.com, Mob:09881303443 and Dr. R. C. Gupta, Assistant Director (Plant Pathology), Mob:09422497764, Chitegaon Phata, Post-Darnasangvi, Taluka-Niphad, Nashik (Maharashtra) 422 003.)
