Sorghum Diseases in India

pathogen and epidemiology of the disease. The
process of pathogenesis and how it is influenced
by flowering biology and environment is not
well understood.
Following are some of the areas that need
research attention in the future:
1. Crop loss. Data showing loss in grain yield
and quality in hybrid seed production and crop
production are needed. Much of the present
seed certification standard for ergot contamination
appears to be arbitrary. Research is also required
to determine practical levels of sclerotia
in seed-lots.
2. Biology. Studies are needed to determine
why sclerotia germinate poorly (e.g., the role of
heterothallism) and to identify conditions that
will improve germinability of sclerotia. Variability
in the pathogen should be studied.
3. Pathogenesis. Histopathology of hostpathogen
interaction should include the routes
of infection (e.g., can the pathogen penetrate the
ovary wall?), and the progress of colonization
until the formation of the fungal stromata and its
differentiation into sclerotia.
4. Flowering biology. The biology of sorghum
flowering is poorly understood. How flowering
biology is associated with opportunities for infection
and how the host-pathogen interaction is
modified by variable flowering behavior due to
altered environmental conditions is largely unknown.
Can the pathogen infect and colonize
the fertilized ovary? Can infection occur prior to
flower opening? Fluorescence microscopy is a
powerful tool for the study of competition between
pollen and conidia.
5. Epidemiology. Environmental conditions
favorable for disease development are largely
known. However, it is necessary to define cool
and humid conditions and develop useful and
nonambiguous terminology for describing a
particular climatic condition. We also need to
know the role of preflowering environmental
conditions on production of primary inocula by
collateral hosts and sclerotia.
6. Disease cycle. Further research should seek
sources of primary inoculum, and determine
how these are maintained and disseminated. Information
on the role of sclerotia in disease cycle
is required.
7. Host resistance. Development of simple, reliable,
large-scale field screening techniques requires
major attention; identification of resistant
242
sources and efficient breeding for resistance is
dependent upon such tools.
Acknowledgment. I wish to thank L.K.
Mughogho for critically reviewing this manuscript.
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