RA 00110.pdf - OAR@ICRISAT

Moderator's Overview
Biological Factors Affecting Pearl Millet
O. Sidibe 1
This session includes five papers concerning three
main areas of pathology, entomology, and soil
microbiology.
Diseases cause much damage to pearl millet crops
in West Africa and India. Disease incidence varies
according to the ecoclimatic conditions, region, and
year.
Downy mildew (Sclerospora graminicola), a major
disease, is more prevalent in West Africa than in
India. After the introduction of hybrids in India in
the 1970s, it has been noticed that mildew and ergot
(Claviceps fusiformis) seriously reduce pearl millet
yield. Smut (Tolyposporium penicillariae) is another
disease that is common in certain agroecological
zones of West Africa and India.
There is not much information on the disease
situation in East and southern Africa. It has been
observed, however, that in similar ecoclimatic conditions,
these diseases are responsible for substantial
yield losses here.
In West and southern Africa, and in India, rust
(Puccinia purpurea) can become a serious problem
under low-temperature conditions, particularly after
flowering.
Insect pests like spike worm (Raghuva albipunctella)
and stem borer (Acigona ingefusalis) cause a
lot of damage. As in the case of crop diseases, the
economic importance of pests has not yet been accurately
determined.
Other yield-reducing pests that should be considered
are weeds, grasshoppers, locusts, birds, and
jerboas. Bacteria and viruses can cause serious diseases.
The economic importance of each of these
factors or group of factors should be determined
since their incidence varies each year from one agroecological
zone to another.
The use of microbia in the rhizosphere for yield
increase is a relatively new area of research, although
it has been well known that certain soil bacteria can
fix atmospheric nitrogen in the soil and that mycorrhizae
increase phosphorus availability. The significant
work done in India on the subject is being
applied in farmers' fields.
Many studies have been carried out but have not
yet resulted in any solutions suitable to farmers,
which also consider socioeconomic aspects and protection
of the ecosystems. The multidisciplinary
approach recommended for integrated control and
intensified training and information given to extension
agents could provide a solution to the problem.
1. Director of Research, CILSS, B.P. 1530, Bamako, Mali.
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