Sorghum Diseases in India

Charcoal rot was observed in drought-stricken
areas of Botswana (Botswana: Ministry of Agriculture
1987), Zimbabwe, the Republic of South
Africa, and possibly Malawi, in particular at research
stations. Page et al. (1985) did not report
charcoal rot damage in pearl millet fields in the
communal areas of Zimbabwe. It appears that
this disease is of minor importance in the region.
Some work to test sources of resistance is ongoing
in Botswana. Many genotypes were susceptible
to charcoal rot at Sebele (Botswana) in
1987 and 1988, but Botswana Serere 7A was relatively
resistant.
Growth deformations are occasionally found
in research plots and in farmers' fields, but the
disease is thought to be of minor importance
only.
Inflorescence diseases
Ergot (Claviceps sp) and smut (Tolyposporium penicillariae)
are major diseases.
Ergot. Many local germplasm collections latesown
in 1987-88 at Henderson and at Panmure
in Zimbabwe were heavily affected under natural
disease pressure. Most of the germplasm, including
introductions tested at Ilonga in Tanzania,
were heavily affected in 1987. Local millet
in farmers' fields was heavily affected at Gairo
in 1987 and in the Singida area in 1988. Pearl
millet in farmers' fields in the Shire Valley was
affected in 1987. Several of the lines developed
for ergot resistance (e.g., ICMPES 28) at ICRISAT
Center showed low severities under natural disease
pressure at several locations in Malawi,
Tanzania, and Zimbabwe during several years.
WC-C75 was moderately susceptible in Zambia.
In 1987, with an ergot pathologist from ICRI­
SAT Center assisting, screening with artificial inoculation
began. Five out of 100 ICRISAT's
ergot-resistant entries had low severities (less
than 10% of inoculated head area affected) after
artificial inoculation. Immunity did not occur.
ICMPES 28 and ICMPES 29 had severities exceeding
30% after inoculation. However, it is
possible that flowering was prolonged because
of out-of-season sowing. Additional utilization
of the ergot-resistant germplasm received from
ICRISAT Center is planned.
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In 1988, sclerotia collection began; these may
be found almost anywhere ergot occurs. Studies
to determine if toxicity is related to genotype
and environment are required. Scientists at Imperial
College (UK) have received sclerotia samples
from many places in southern Africa for
future studies.
Smut. Smut is important in many pearl millet
growing areas of southern Africa. At certain locations,
e.g., at Ngabu in Malawi; at Hombolo in
Tanzania; and at Panmure in Zimbabwe, smut
appears to compete with ergot for infection sites
in the pearl millet head.
In 1986 and 1987, genotypes developed at
ICRISAT Center had low smut severities under
natural disease pressure in Malawi and Zimbabwe,
in particular ICMPES 28, ICMPES 29,
ICMPS100-5-1, and ICMPS 900-9-3.
In 1988, in cooperation with Wye College,
UK, testing of artificial methods of inoculation
and studies of the smut life cycle were initiated.
Witchweeds
Pearl millet is affected by Striga asiatica and
S. hermonthica (Riches et al. as reported in
SADCC/ICRISAT1987).
Striga asiatica. Pearl millet is generally said to
be resistant to this witchweed in southern Africa.
Only on rare occasions will a single plant be
found in a field of millet in Botswana (Riches et
al. as reported in SADCC/ICRISAT 1987); the
same is reported from Hombolo in Tanzania. In
the Masvingo region of Zimbabwe, pearl millet
fields are commonly affected. Little is known of
the extent of the damage caused by S. asiatica in
pearl millet.
Striga hermonthica. In the northern districts of
Tanzania, this parasite is of importance on sorghum
and possibly on millets. At least two
strains of the parasite, one specific to pearl millet
and the other specific to sorghum have been reported
in Sudan (Wilson-Jones 1955). At Ukiriguru
Research Station in Tanzania, it was
observed that sorghum was heavily affected,
while on Serere 17A hardly a Striga plant was
found. It must be determined if such physiological
strains occur in the region, in particular in
Tanzania.