Bacterial leaf spot of sesamum

1. Prepared by: Akashdeep Sutradhar.
BSc. Agri. 3rd yr(Vth sem.)
.

2. Sesame field

3. INTRODUCTION
This is one of the few major diseases of
sesame in India, which occurs also in
Uganda, Brazil, U.S.A. and Sri Lanka. It
occurs wherever the crop is grown. In
some years it occurs in epiphytotic form,
blighting the leaves and reducing grain
yield up to about 50%.
Name of host pathogen: Pseudomonas syringae pv. sesami

4. Symptoms
The disease first
manifests itself on the
leaves as minute water-
soaked lesions, which
enlarge to form round to
irregular spots 5-15 mm in
diameter on both leaf
surfaces.
The spotted area is light
brown to white in the
beginning which later
becomes dark grey.

5. Symptoms of leaf spot at
beginning stage.
Some
more
effected
leaf and
plant
part.

6. cont.
Often infection takes
place on the leaf
petiole, stem and pods,
producing dark
coloured, deep-seated
lesions.
The damage depends
on the severity of
infection on the stem
and pods and the stage
at which the infection
takes place.

7. Causal Organism:
The hyphae of the mycelium in the host are
irregularly septate, light brown coloured and
thick walled. They produce conidiophores in
clusters, which emerge through the stomata
and bear the conidia on the surface. The
conidiophores are light brown coloured at the
base, more or less hyaline at the tip, 0-3
septate, and measure 38-67 x 4 micron. The
conidia are whip-like, hyaline to light yellow,
thin walled, 7 to 10 septate and measure 90-
136 x 3-4 micron.

8. Disease Cycle
The fungus is seed-
borne, both internally
and externally, but can
also survive in the
plant debris. This,
primary infection in the
field may be from seed
and infested plant
debris and secondary
spread may be through
wind-borne conidia.

9. Control
The externally seed-borne fungus can be
eradicated by chemical seed treatment.
treat the seed with hot water for about 30
minutes at 53 degree C.
Secondary infection can be checked by
fortnightly with 1% Bordeaux mixture.