Sorghum Diseases in India

National Research Efforts
Crop improvement efforts are underway in most
countries of Central America. Resource-poor
farmers prefer to save seed from their own
crops, rather than buy seed each year. This sustains
the demand for open-pollinated varieties.
In El Salvador there have been releases of improved
maicillo varieties suitable for intercropping.
Many improved (photoperiod-insensitive)
sorghum varieties and hybrids have also been
released; open-pollinated white-seeded varieties
are available for making tortillas, red-seeded
hybrids for grain production are intended for
animal feed, and sorghum-sudan hybrids have
been released for use as forage crops (Clara et al.
1984).
Photoperiod-sensitive hybrids are being
developed in El Salvador in an effort to reach
higher yields under the maize-sorghum intercropping
system.
In the Honduras there have been releases of
white-seeded open-pollinated varieties for tortillas,
and a hybrid for animal feeds. Guatemala
has a similar hybrid. In addition, maicillos are
being improved for yield and for disease resistance
in the Honduras and will soon be ready
for release.
Large-scale sorghum sowings frequently
make use of imported hybrids, particularly in
Costa Rica, Panama, and Dominican Republic,
and to an increasing extent in Guatemala. However,
these must undergo local and regional
evaluations that include overall adaptability,
yield, and disease resistance. Field screening for
SDM resistance, for instance, is done at Comayagua,
the Honduras.
SDM was first reported in Central America in
1975. Since then, El Salvador's sorghum program
has included greenhouse screening for
SDM resistance. The disease spreads rapidly
throughout the region, much to the concern of
sorghum and maize workers. Because of this, a
cooperative effort was made to find SDM-resistant
materials in the Central American region
(Fernandez and Meckenstock 1987). In 1979, the
experiment station of Las Playitas in Comayagua
was designated the site for all interested
national programs of the region to send
their maize and sorghum cultivars for field evaluation.
At that time, there were no reports of
different pathotypes of this fungus. Now that
several pathotypes are known to occur in the
Honduras, the pathogen populations need to be
monitored throughout the areas where SDM is
known to exist. Once the pathotype is identified,
corresponding sources of resistance can be
introduced.
In the past, there has been a widespread tendency
to downplay the importance of foliar diseases.
There is no question now concerning the
importance of these diseases in the Honduras
(Table 2). Although sorghum improvement efforts
in the region have included a concern for
plant health in general, it is hoped that a more
concentrated effort will be made in the future to
develop and release materials that possess
higher degrees of resistance to the most important
diseases. Sources of resistance to many important
diseases have already been identified
(Meckenstock and Wall 1987).
Table 2. Yield losses of grain sorghum from
foliar diseases in the Honduras. 1
Table 2. Yield losses of grain sorghum from
foliar diseases in the Honduras. 1
Extent or duration Yield loss
Disease of infection (%)
Gray leaf spot < 20% vs 100% 2
15
Zonate leaf 310 vs 993 14
spot AUDPC 3
Oval leaf spot