Sorghum Diseases in India

provided during dry spells. Spreader rows of
susceptible varieties were grown at the borders
and inside the nursery. Considerable success has
been achieved in increasing the inoculum on
sorghum seed, and methods of artificial inoculation
are now being investigated. Locally bred
advanced lines are also being tested for leafblight
resistance.
Ergot in pearl millet With the help of SADCC/
ICRISAT, a procedure for inoculating pearl millet
with the ergot pathogen was established.
Heads of test lines were bagged at the booting
stage, inoculated with a spore suspension at
time of maximum stigma emergence, and rebagged
to maximize humidity and ensure
infection.
Work remaining
1. Develop reliable screening techniques for
rusts and smuts in these cereals.
2. Conduct screening programs in the laboratory
or greenhouse in order to control environmental
variables.
3. Conduct epidemiological studies to gain
knowledge useful in development of diseasemanagement
packages for communal farmers.
4. Seek cultural practices that may reduce disease
incidence.
5. Determine yield losses caused by the major
diseases.
6. Study seedborne pathogens of sorghum and
millet.
Discussion
Since the beginning of Zimbabwe's sorghumimprovement
program, leaf blight, ergot, downy
mildew, and covered kernel smut have been
identified as the major and most widespread
sorghum diseases in the country (Sanderson
1967, pp. 17-23; Rattray 1968; Brown 1973;
Graham 1972). The widespread occurrence of
these diseases may be in part because some
(such as downy mildew) also occur in maize.
Close rotation of these cereals with maize enhances
the chances of survival and spread of the
pathogens, in communal areas, especially in region
III, maize is also grown and because land is
6
limited, rotation with maize is likely. In regions
IV and V, rainfall is more limited, and the close
rotation with maize is less common. This practice
tends to create natural 'sick plots' for endemic
pathogens like Sporisorium reilianum. Also
contributing may be the seedborne nature of
these pathogens (Noble et al. 1968). Most communal
farmers keep their seed and do not treat
it, permitting the pathogen to remain endemic.
Ergot, widespread in the Mashonaland Central
Province, is serious in cytoplasmic male-sterile
lines. Consequently, hybrid seed production in
this area can be impaired severely. The hazards
of ergot in livestock feed cannot be overemphasized.
A practical method for control of ergot
must be found.
Seed-health testing (plant quarantine) has
been neglected in Zimbabwe. It is possible that
new diseases may be introduced by pathogens
arriving on or in seed. A number of the pathogens
of pearl millet and sorghum have been reported
to be seedborne (Noble and Richardson
1968). There is insufficient evidence, however, to
confirm seedborne dissemination of a number of
pathogens of these cereals.
Recent pest and disease surveys in communal
areas by Plant Protection Research Institute
(1987) personnel have revealed a close association
of nematodes and stunting in both sorghum
and pearl millet. Pratylenchus zea, P. branchyurus,
Rotylenchus pawns, and Paralongidorus sp were
identified during these surveys. Meloidogyne javanica
caused serious stunting and chlorosis to
finger millet (Page et al. 1985). However, the
general economic importance of nematodes on
sorghum and pearl millet is an open area for
investigation in Zimbabwe.
Conclusion
The phytopathological research on sorghum and
millets diseases in our country has been slow
and insufficient. This is mainly due to shortage
of trained manpower, especially in the areas of
phytobacteriology and plant virology. Shortages
of transport and equipment are logistical constraints.
The Government of Zimbabwe is aware
of these needs and is making an effort to provide
resources, and we feel the situation will improve
considerably in the near future.
Acknowledgment. I wish to express gratitude