A field experiment was conducted at the research farm of Sher-e-Bangla
Agricultural University, Dhaka. Bangladesh during the rabi season of 2006-07 to
study the management of purple blotch of onion through chemicals and plant
extracts. The experiment was laid out in a Randomized Complete Block Design
(RCBD) with 3 (three) replications. Eleven treatments comprising Dithane M-45,
Rovral 50WP. Bavistin 50WP. Cupravit 50WP, Proud 250 EC, Champion, Tilt
250 EC, Ridomil Gold. Neem leaf extract. Alamanda leaf extract and Control were
tested in the experiment. A positive and significant effect of fungicides and plant
extracts was found on the management of purple blotch of onion including,
germination, plant height, bulb diameter and bulb yield of onion. The highest bulb
yield (8.767 t/ha) and bulb diameter (3.787 cm) were obtain with Rovral 50WP.
The percent plant infection, percent leaf infection, percent Leaf Area Diseased
(%LAD) and Percent Disease Index (PDI) were found the lowest in foliar spray
with Rovral 50WP. Between the two plants extracts Neem leaf extract performed
better then Alamanda leaf extract.