Citrus canker incited by Xanthomonas axonopodis pv. citri (Hasse) Vauterin et al. is a serious disease
of acid lime [Citrus aurantifolia (Christm.) Swingle] all over the world including West Bengal, India.
The disease depends much upon its secondary spread through rain splash, mechanical contact in
stormy weather and leaf damage by citrus leaf minor (Phyllocnistis citrella Stainton). For controlling
citrus canker the usual recommendation includes antibiotics and some agrochemicals in the form of
spraying. Little work has been reported on biological management of the disease. An experiment was
set up in a farmer’s field (acid lime orchard), Nadia, West Bengal, using an inhibitory strain of
Bacillus subtilis (S-12) during 2009-2010. Single spray of aqueous suspension (2.7 x 109 cells/ml) of
bacterial cells was spread on 5 batches (6 numbers of plants/batch) of plants keeping 4 batches
unsprayed. Per cent Disease Index (PDI) was recorded throughout the year at every month using 0-4
scale from both treated and untreated plants. Initial PDI was also taken before one week of spraying. A
single spray of the bacterial suspension during the peak season for disease that is in July has resulted
in a satisfactory decline of the disease. A sharp decline of the disease was recorded at 20 days after
treatment indicating that the spore forming bacteria might have taken over on the leaf surfaces of the
plants