An experiment was conducted during the Rabi season of 2014-2015 at the farmers field of Pearpur, Faridpur Sadar, Faridpur under the supervision of On-Farm Research Division (OFRD), Bangladesh Agricultural Research Institute (BARI), Faridpur to investigate the effective control method of purple blotch of onion during seed production and to develop ecofriendly and cost minimizing approaches for controlling purple blotch. The experiment was conducted using eight treatments viz., T1= Combination of Iprodione and Mencozeb with Metalaxil 4 times spray @ 2 gL-1 water each, T2 = Iprodione + Fenamidon with Mancozeb + Propineb + Mancozeb one time alternative spray each @ 2 gL-1 water for 4 times, T3 = Combination of Iprodione and Mencozeb with Metalaxil 2 times spray @ 2 gL-1 water each + Trichoderma harzianum one time spray @ 50 mlL-1 water + Sanitation (25% removal of infected leaves at 77 DAP), T4 = Trichoderma harzianum two times spray @ 50 mlL-1 water + Combination of Iprodione and Mencozeb with Metalaxil 1 time spray @ 2 gL-1 water each + Sanitation, T5 = Trichoderma harzianum compost used during final land preparation @ 50 g m-2 water+ T3, T6 = Trichoderma harzianum compost used during final land preparation + Trichoderma harzianum 3 times spray @ 50 mlL-1 water + Sanitation, T7 = Difenconazole 2 times 1 mlL-1 water + combination of Iprodione and Mencozeb with Metalaxil 2 times spray @ 2 gL-1 water each and T8 = Control. Successful control of purple blotch of onion was achieved by spraying fungicide (chemical plus bio) in treatment T5 followed by T3 and T4 treatment. The highest seed yield was 580 kg ha-1 obtained from the treatment T5 in onion seed crop. The highest BCR (3.92) was calculated from T5 treatment and the lowest from T8 (2.78).
Key words: Integrated approach, Onion, Percent Disease Intensity, Purple blotch, True seed production
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