Sorghum Diseases in India

sp, Cercospora fusimaculans, Phyllachora sp, and
Bipolaris urochloae) and rust (Puccinia penicillariae)
caused foliar diseases (Riley 1960; Angus
1965; FAO 1972; Peregrine and Siddiqi 1972;
Kenneth 1975; Rothwell 1983; and Plumb-
Dhindsa and Mondjane 1984.)
Downy mildew
In Tanzania, Malawi, Mozambique, Zambia, and
Zimbabwe, local germplasm can become heavily
affected with downy mildew (DM). However,
when downy mildew differentials were tested
under natural disease pressure, BJ 104, BK 560,
MBH 110, WC-C75, and ICMS 7703 were resistant
(less than five infected plants per 4.5-m
row) and 7042 DMS and Impala Seed (Zimbabwe
local) were susceptible at three sites—
Ngabu (Malawi), Lusitu (Zambia), and Wedza
(Zimbabwe). This suggests a weak pathogenicity
of the downy mildew at the sites of testing.
Ball (1987), using isolates from the same
sites, had similar results in experiments in plastic
tunnels in the UK.
The majority of the germplasm developed at
ICRISAT Center and in western Africa appeared
to have a good level of resistance. However,
there appears to be a need to identify susceptible
germplasm and confirm resistance with controlled
disease pressure.
False mildew
The disease was recorded on klits grass (Setaria
verticillata) in 1926 and reported on pearl millet
in 1952, but high severities on pearl millet were
observed for the first time in Zimbabwe in the
1985/86 cropping season (Mtisi and de Milliano
1991). The disease appeared to be favored by
moist conditions (i.e., wet years). The host range
appears to be limited to genera of the Graminea
family. Genetic resistance was found in introductions
(e.g., 700516, 7042 DMR, ICMPES 29,
and ICMPES 1500-7-3-2) and in entries of the
Regional Cooperative Variety Trial (e.g., IVS-
A82, and IBVM 8402 SN). Most entries from the
Pearl Millet Dwarf Variety Trial including RMP1
and GAS from Zimbabwe were moderately susceptible
in Zimbabwe. Very little is known concerning
the influence of false mildew on yield,
but the indications are that yield is affected only
to a minor extent (de Milliano as reported
in SADCC/ICRISAT 1987). Confirmation is
required.
Leaf spots
At certain locations in Malawi (e.g., at Ngabu in
1987), Tanzania (e.g., at Hombolo in 1988) Zambia
(e.g., at Kaoma in 1986 and 1987), and Zimbabwe
(at Henderson in 1986 and 1987; at Kadoma, 1986;
at Matopos, 1986; and at Wedza, 1986), pearl millet
was affected by leaf spot diseases. Highly susceptible
lines, such as 7042 DMR, occasionally
failed to produce seed (e.g., at Henderson, 1987).
Genetic resistance appeared to be present, at least
at certain locations in certain introductions (e.g.,
700516 and ICMPES 28). The causal organisms
still are not all known and identification is ongoing
with assistance of the International Mycological
Institute, Kew, UK.
With assistance of scientists from ICRISAT
Center, it was found that Bipolaris urochloae affected
pearl millet in Zimbabwe (Singh 1987;
Sivanean 1987). Disease identification, determination
of yield losses, and elimination of very
susceptible genotypes need further attention.
Rust
Rust may be of some importance in a few countries,
such as Tanzania. From 1986 to 1988, the
gene for rust resistance in 7042 RR appeared to
be effective in Malawi, Zimbabwe, and Tanzania.
P 1564 was immune in Zimbabwe (at
Mzarabani) but moderately susceptible in Tanzania
(at Ilonga). Similarly P 24-1 was immune
in Malawi (Ngabu) but susceptible in Tanzania
(Ukiriguru). BJ 104 DMR was susceptible in
Zimbabwe (Mzarabani) but resistant in Tanzania
(Ukiriguru). This may indicate that there are differences
in rust populations in southern Africa.
Additional sources from ICRISAT Center and
elsewhere will be screened for resistance to rust,
in search of resistant lines that are better agronomically
than 7042 RR.
Stalk and root rots
Charcoal rot (Macrophomina phaseolina) and possibly
Fusarium spp caused stalk and root rots.
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