EFFECT OF CHEMICALS AND ENVIRONMENT FRIENDLY COMPONENTS FOR THE MANAGEMENT OF PURPLE BLOTCH OF ONION

Abstract

A set of experiment were conducted at the laboratory of the Department of plant Pathology, SAU and Spices Research Centre (SRC), BARI, Shibgoanj, Bogra, Bangladesh, during the month of September-October in 2010. Field experiment was conducted at spices Research Centre, BARl~ Shibgonj, Bogra to determine' the integrated approach for the management of purple blotch of onion for seed production during October, 2010 to March 2011. The treatment of the expeirment were Rovral wp @ 0.2% (TI), Rovral wp @ 0.1% + Provax 0.25% (T2); Trichoderma 5xl06 spore/ml @ 100 ml/plant (T3); Rovral wp @ 0.1% + Bavistin 0.5% (T4); Neem leaf extract 1:6 (w/v) (Ts); Rovaralwp @ 0.1% +Evaral @ 0.1% (T6); Rovaral wp @ 0.1% +Ridomil gold MZ-72 @ 0.1% (T7); Rovaral wp @ 0.1% +Secure @ 0.05% (Ts) andcontrolf'Ts). Different treatment has effect: on inhibition of mycelial growth of the fungus. The lowest mycelial growth was recorded in case of T7 followed by T2 where the highest mycelial growth was recorded in cas~ of control (T9). In field experiment, the lowest disease incidence (both on leaf infection and stalk infection) were recorded incase of treatment T7 ii•.comparison to other treatments irrespective of days after transplanted while highest disease incidence was recorded in control treatment (T9). The disease severity were also recorded the' lowest in case of treatment T7 followed by treatment T2. The highest PDI was recorded in control treatment. The disease incidence and severity were increased gradually with the age of the plant but the increasing rate was the lowest in treatment T7 and highest in control (T9)' The highest plant height (81.40cm) and the yield (1.24 ton/ha) were recorded in treatment T7 where as the lowest plant height (6I.20cm) and seed yield (0.82. tonlha) were recorded in control (T9)'