Sorghum Diseases in India

strains produced a hypersensitive response in
tobacco.
The average doubling times for P. avenae,
P. andropogonis, P. rubrilineans, P. rubrisubalbicans,
and the millet pathogen were 103,148,100,
110, and 108 minutes, respectively.
Pathogenicity tests
Pathogenicity of various P. avenae, P. rubrilineans,
and P rubrisubalbicans strains was determined
on maize: Pioneer 3195 (Pioneer Hi-Bred
International, Johnston, IA) Gold Cup (Harris-
Moran Seed Co., Rochester, NY); grain sorghum
(Sorghum bicolor): 80B3039 (D. T. Rosenow, Texas
A&M University, Lubbock, TX); pearl millet:
Sidney dwarf and Serere 3A (D. J. Andrews,
University of Nebraska, Lincoln, NE); and sugarcane
(Saccharum officinarum): cultivar 67500
(N. Zummo, Mississippi State University, Mississippi
State, MS). Cultures were grown at 28 °C
overnight in NBY, centrifuged at 13 000 g for 10
140
min; resuspended and then centrifuged and
washed with 12.5 mM PO4 buffer two additional
times. The cell concentration was adjusted to 100
Klett units. Leaves were inoculated, 2 weeks after
emergence, using a Hagborg device. Inoculated
plants were maintained in a greenhouse
(22-28 °C) with automated misting (6 min h -1 for
6 h day -1 ). Symptoms were recorded 2 weeks
after inoculation. All P. avenae isolates tested
were pathogenic to maize, sorghum, millet, and
sugarcane.
On maize, lesions were translucent with light
tan centers and dark brown margins. The margins
of the lesions were usually water-soaked
and confined to interveinal tissue. Lesions on
sorghum had tan centers with dark red margins
(Fig. 3). Leaf veins in proximity to the margin
were dark red. Lesions on millet were light
brown in the centers and dark brown at the margins,
up to 10 cm in length, and found only on
tissue between leaf veins. Water-soaking was
observed only at the edge of the margin. On
sugarcane, elongated dark red lesions up to 45
cm long were confined to interveinal tissue.
Figure 3. Bacterial leaf blight on sorghum cv B 35-6 caused by Pseudomonas avenae.