Abstract

Garlic (Allium sativum), one of the most important spice crops in Bangladesh, is affected by a variety of fungal diseases. Among them, Stemphylium blight is topmost disease which limits the quality and quantity of both vegetative growth as well as yield of garlic. The study was carried out under both in vitro and in vivo conditions to evaluate the efficacy of both individual and integrated application of bioagents, inducers like salicylic acid and chitosan with chemical fungicides, Iprodione (Rovral 50 WP) against Stemphylium blight of garlic. The in-vitro antagonism test was conducted using five strains of each of the Bacillus subtilis and Pseudomonas fluorescens where the highest percent inhibition of mycelium growth was found in Pseudomonas fluorescens strain Psf3 (57.04 %) and Bacillus subtilis strain Bacs4 (54.44 %). A total of 10 treatments were applied in the field. Treatment T6 (Rovral @ 0.2 % + Pseudomonas fluorescens strain Psf3 @ 10 mL (106 CFU/ml) / 5 plant) showed the lowest disease severity (38.4 %). This treatment also exhibited promising result in both the vegetative and yield parameters of garlic under field conditions. The highest bulb yield (6.23 ton/ ha) was found in T6, surpassing all individual treatments. This finding denoted the positive synergistic effect of combined application of Rovral 0.2 % and Pseudomonas fluorescens strain Psf3 for sustainable management of Stemphylium blight. The combined application of chemical and bioagents is more feasible and practical for managing Stemphylium blight disease of garlic as well as for getting better yield in field condition.

Key words: Garlic, Stemphylium blight, IDM, Biological Control Agent, Inducer