Abstract:
An investigation was carried out in the seed health laboratory of the Department
of Plant Pathology and in the farm of Sher-e-Bangla Agricultural University to
evaluate the effect of selected fungicides and micronutrients against Alternaria
porri and Stemphylium vesicarium causing purple blotch complex of onion.
Four chemical fungicides, viz. Rovral 50 WP, Dithane M-45, Ridomil gold and
Cupravit and micronutrients (ZnSO
+ Borax) were assayed alone and in
combination in the investigation. In in vitro test Rovral 50 WP (0.2%) showed
the promising result against mycelial growth of Alternaria porri and
Stemphylium vesicarium that reduced the mycelial growth by 69.00% and
76.56% respectively followed by Dithane M-45. In the field experiment, the
fungicides were tested alone and in combination with micronutrients (ZnSO
4
+
Borax), comprised with ten treatments. Among those treatments, the application
of chemical fungicide in combination with micronutrients always performed
better than the application of chemical fungicide alone in controlling purple
blotch complex of onion. Rovral 50 WP (0.2%) + Micronutrients reduced the
disease incidence (% Leaf infection) and disease severity (% Leaf area diseased)
4 by 20.92% and 44.88%, respectively followed by Rovral 50 WP (0.2%) alone,
Dithane M-45 (0.45%) + Micronutrients and Dithane M-45 (0.45%) alone. The
bulb yield and yield contributing characters viz. plant height, plant dry matter,
root length and weight were found significantly higher in case of application of
Rovral 50 WP (0.2%) + Micronutrients where yield was increased by 36.88%
over control.
Description:
A Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University, Dhaka
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
IN
PLANT PATHOLOGY
SEMESTER: JULY – DECEMBER, 2008
