Sorghum Diseases in India

sowing of the ZSV 1 spreader rows and later
sowing (by about 3 weeks) of the test entries.
QL 11 was symptomless for 3 years in the sick
plot; QL 3 was symptomless in 1986 and 1988,
but showed a mild mosaic in 1987. Local germplasm,
locally developed varieties, hybrids,
and foreign introductions, showed chlorosis at
altitudes from 100 to 1670 m in several countries.
In Zambia, Johnsongrass (Sorghum halepense)
showed chlorosis after natural infection in 1986.
In South Africa, both maize dwarf mosaic and
sugarcane mosaic virus have been reported, and
the latter appears to be increasing in importance
(McLaren, personal communication 1988). Virus
has not been officially reported in sorghum in
Lesotho, Swaziland, Zambia, or Zimbabwe. Virus-like
symptoms were observed in Zimbabwe
from 1986 to 1988 and in Swaziland in 1987. It
was established that the virus in Zambia differs
serologically from the virus on sorghum in India
(Reddy 1987).
Of the 106 grass species tested for resistance
to virus by Rosenkranz (1987), 29 are present in
Zimbabwe (National Herbarium and Natural
Botanic Garden, personal communication 1987).
Of these, six were susceptible and seven moderately
susceptible to the viruses in Mississippi
(Rosenkranz 1987). Several of the grasses, such
as Echinochloa colona, Digitaria ciliaris, and Eragrostis
ciliaris, are common in the region. It needs
to be determined if these grasses can serve as
reservoirs for viruses infective to sorghum.
B. Bacterial diseases
Bacterial leaf streak (Xanthomonas campestris
pv holcicola). It is considered important in
Angola (Marcelino, personal communication
1988) and in the Republic of South Africa
(McLaren, personal communication 1988). Bacterial
leaf streak and possibly leaf stripe symptoms
were common on sorghum varieties and
sudangrass in Lesotho (Qhobela et al. 1986, pp.
9-42).
Bacterial stripe (Pseudomonas sp). It occurred
in several other countries (Rothwell 1983; Shao
1984). Plant quarantine regulations of Malawi
and the Republic of South Africa require that
imported seed be free from Pseudomonas andropogonis
(Williams et al. 1980; McLaren, personal
communication 1988). In 1986, cooperative
14
efforts by SADCC/ICRISAT and Kansas State
University, USA got underway; its purpose is to
learn more about pathogenic bacteria affecting
sorghum. In Zambia, bacterial symptoms were
observed but the pathogen or pathogens were
not identified (Angus 1965, 1966). The loss in
biomass caused by bacteria on sorghum in the
region requires quantification.
C. Fungal diseases
Eight fungal foliar pathogens: Cercospora sorghi,
Colletotrichum graminicola, Exserohilum turcicum,
Gloeocercospora sorghi, Peronosclerospora sorghi,
Ramulispora sorghi, R. sorghicola and Puccinia purpurea
commonly occur in the region (Angus
1965, 1966; Williams et al. 1980; Rothwell 1983;
Plumb-Dhindsa and Mondjane 1984; Shao 1984;
Qhobela et al. 1986; Botswana: Ministry of Agriculture
1987; and McLaren, personal communication
1988). Their economic importance is not
known. In 1986, cooperative efforts with Texas
A&M University and ICRISAT got underway,
working with downy mildew and the isolation,
culturing, and screening of leaf spot diseases.
Anthracnose. It is recorded in seven countries of
southern Africa (Table 2). In 1987 at Mansa,
Zambia, a good number of entries from the
Zambian program and ICRISAT were susceptible
to anthracnose. In the 1987/88 season, with
the assistance of an ICRISAT Center scientist,
SADCC/ICRISAT began screening for resistance
to anthracnose in Zambia. In 1988, it was
confirmed that certain sorghums, including several
lines resistant to anthracnose in India during
the last 10 years, were susceptible at several
research stations in Zimbabwe.
Leaf blight. Since the 1986/87 season, the
SADCC/ICRISAT program is assisting scientists
with the Zimbabwe Sorghum Improvement Program;
the purpose is to develop expertise in
screening for resistance to leaf blight. In Zimbabwe,
Gwebi (17°41'S latitude, 30°52'E longitude,
1448 m altitude, 826 mm rainfall) and
Henderson (17 °35'S latitude, 30°58'E longitude,
1292 m altitude, 869 mm rainfall) regularly had
leaf blight epiphytotics. Some white-grained
sorghums showing resistance to leaf blight at
Gwebi during the last 2 years were Siloe Best,
Nyakosaba Best, and Tenant White (Lesotho),