Neem in India
Bacterial leaf, blight and shot hole
The disease is caused by Xanthomonas campestris PV. Azadirachtae (Desai, Gandhi, Patel and
Kotasthanae 1966) Dye. First symptoms appear on the leaflets as small translucent, water-soaked
spots, which turn brownish. These spots gradually increase in size, coalesce and become necrotic
from the centre. The coalesced lesions are often delimited by veins and veinlets giving angular
appearance. The infected leaves eventually become chlorotic dry and defoliate prematurely. The
diseased tissue frequently falls-off giving shot holes. Leaflets showing blight symptoms have a
narrow band of translucent water-soaked area on either or both the sides of mid-veins or veins arising
from them. The pathogen is detected in the vascular bundles of the petioles of blighted leaves.
Petioles also have narrow water-soaked streaks full of bacteria
Disease spread is favoured by spattering rains, whereas disease development is maximum at mean
ail temperature of 22-270C. Bacteria in infected leaves survive temperatures of 0-6C for 10 days. The
pathogen is found to be host specific.
The disease is caused by Xanthomonas campestris PV. Azadirachtae (Desai, Gandhi, Patel and
Kotasthanae 1966) Dye. First symptoms appear on the leaflets as small translucent, water-soaked
spots, which turn brownish. These spots gradually increase in size, coalesce and become necrotic
from the centre. The coalesced lesions are often delimited by veins and veinlets giving angular
appearance. The infected leaves eventually become chlorotic dry and defoliate prematurely. The
diseased tissue frequently falls-off giving shot holes. Leaflets showing blight symptoms have a
narrow band of translucent water-soaked area on either or both the sides of mid-veins or veins arising
from them. The pathogen is detected in the vascular bundles of the petioles of blighted leaves.
Petioles also have narrow water-soaked streaks full of bacteria
Disease spread is favoured by spattering rains, whereas disease development is maximum at mean
ail temperature of 22-270C. Bacteria in infected leaves survive temperatures of 0-6C for 10 days. The
pathogen is found to be host specific.
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