Sorghum Diseases in India

Nematology
1. Data on the role of nematodes in sorghum
production in the developing nations are extremely
limited. A major reason is the small
number of scientists, in most of the developing
nations, who can adequately assess nematode
problems. National scientists with
postgraduate training in plant nematology
are urgently needed.
2. Identification and documentation of the
pathogenicity and relative aggressiveness of
nematodes associated with sorghum production
is incomplete.
3. Distribution of pathogenic nematode species
among sorghum-producing nations of the
world is poorly understood. Frequency distributions
and population densities are needed
to assess the worldwide impact, relative to
other pathogens and pests, of nematodes on
sorghum.
4. Diversity in nematode population dynamics
attributable to farming practices (traditional
vs. recently adopted practices) is unknown or
poorly understood. The influence of cropping
sequences, mixed cropping vs. intercropping,
cultural practices, and practices to improve
moisture-holding capacity, modify soil structure,
or influence biological activity in soils on
nematode population densities requires investigation
in many nations.
5. Literature on plant-parasitic nematodes and
the diseases they cause is poorly distributed;
in some cases it does not exist. Development,
publication, and distribution of field guides
covering the symptomatology of nematode
diseases is needed.
6. Identification of resistance/tolerance sources
in sorghum germplasm deserves high priority.
The nematode tolerance/resistance characteristics
of sorghum germplasm have not
been determined. Resistance/tolerance in a
sorghum genotype will be species specific.
New techniques to screen germplasm effectively
and efficiently may be required.
Seed Rots and Seedlings Diseases
1. There are sufficient instances of seedling diseases
being a contributing factor in poor
stand establishment in sorghum and occasionally
in millet, but occurrence is spo­
radic—indicating a strong environmental
interaction.
2. With this in mind, research is needed to:
a. Determine the relative contribution of biotic
and abiotic components in stand-establishment
problems, specifically (i) hostrelated
genetic factors (e.g., seedling vigor)
and seed quality, (ii) role and identity of
pathogens and saprophytes and their interactions,
and (iii) environmental factors
and frequency of deleterious or conducive
environments and their interactions with
host and pathogen development.
b. Establish economic importance of (i) seed
dressings, (ii) high-quality seeds, (iii) seedbed
preparation, and (iv) development of
resistance to indicated pathogens and/or
tolerance to negative soil environments.
Grain Mold (GM)
1. Fungi have been implicated in grain deterioration,
but how, when, and in which tissues
these fungi cause damage is poorly understood.
Thus there is need for experiments designed
to:
a. Determine the location of infection and
colonization of specific fungi at different
stages of host maturity.
b. Determine the response of specific hostplant
tissues to microbial attack and elucidate
the respective roles of maternal and
true seed tissues in microbial deterioration
of grain. This approach should include, but
not be limited to, the use of histochemical
and histoserological techniques.
2. Procedures used in different parts of the
world to evaluate grain deterioration should
be compared and, if possible, standardized.
Accurate assessment of host maturity at the
time of evaluation is critical.
3. Select a set of cultivars to be grown, using a
standard procedure, in different parts of the
world for evaluation of GM damage. Current
techniques for inducing microbial seed deterioration
(e.g., Fusarium moniliforme inoculation
at anthesis, sprinkling, etc.) should be
used in these nurseries.
4. Continue studies of the heritability and number
of genes involved in specific mechanisms
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