Sorghum Diseases in India

Sorghum and Pearl Millet Pathology in Zimbabwe
E. Mtisi 1
Abstract
The important sorghum diseases in Zimbabwe are leaf blight (Exserohilum turcicum), ergot
(Sphacelia sorghi), and downy mildew (Peronosclerospora sorghi). In pearl millet the major
problem diseases are ergot (Claviceps sp) and smut (Tolyposporium penicillariae). Methods of
screening for resistance to these major diseases are outlined and plans for future work on sorghum
and pearl millet pathology in Zimbabwe presented.
Introduction
Maize (Zea mays), sorghum (Sorghum bicolor),
and pearl millet (Pennisetum americanum) are the
principal sources of carbohydrates for a majority
of the Zimbabwean population. Sorghum and
pearl millet are particularly important in natural
regions III, IV, and V (Fig. 1). These areas are
marginal in rainfall and soil fertility; maize sowings
here often fail. Most of the land occupied by
communal farmers lies in these regions. Some
commercial farmers grow sorghum in the highrainfall
areas, where the crop out-yields maize in
late sowings (Sanderson 1967, pp. 17-23). Landrace
pearl millet cultivars in the communal areas
yield around 0.5 t ha -1 (Muza et al. 1986). Sorghum
produces from 0.5 to 0.9 t ha -1 (Kyomo
and Keswani 1987; Mushonga, personal communication).
Low yields are also attributed to additional
constraints, including insect pests, nematodes,
diseases, and bird damage.
Zimbabwe's progress in improvement of varieties
and cultural practices has increased
yields to about 2 t ha -1 for pearl millet (Muza et
al. 1986) and 2.5 to 3 t ha -1 for sorghum in areas
with rainfall averaging 500 mm per annum
(Brown 1973). Where rainfall is adequate, sorghum
yields of 7 t ha -1 have been achieved
(Brown 1973; Mushonga 1984). The present need
is to sustain and improve this yield, perhaps by
improving disease resistance in plants.
In the past, research in sorghum and pearl
millet pathology was on a small scale (Mushonga
and Appa Rao 1986), and most of the attention
focused on diseases of commercial crops.
However, our plant breeders at Zimbabwe's Department
of Research and Specialist Services
have tried to incorporate disease resistance into
our national sorghum and pearl millet improvement
programs. Most screening for disease resistance
in these crops has been carried out
under natural epiphytotics (Mushonga 1984;
Muza et al. 1986). Screening for ergot (Claviceps
fusiformis) resistance in pearl millet is an exception
(Mushonga 1983).
Since Zimbabwe's independence in 1980 and
with the establishment at Matopos of the
SADCC/ICRISAT Sorghum and Millets Improvement
Program in 1984, sorghum and pearl
millet pathology are receiving more attention.
Sorghum and Pearl Millet
Disease Situations
National surveys of disease-pest incidence and
severity during 1985, 1986, and 1987 revealed
that sorghum is subject to attack by leaf blight
1. Plant Pathologist, Plant Protection Research Institute, Research and Specialist Services, Box 8100, Causeway, Harare, Zimbabwe.
Mtisi, E. 1992. Sorghum and pearl millet pathology in Zimbabwe. Pages 3-7 in Sorghum and millets diseases: a second world
review, (de Milliano, W.A.J., Frederiksen, R.A., and Bengston, G.D., eds).'Patancheru, A.P. 502 324, India: International Crops
Research Institute for the Semi-Arid Tropics.