Sorghum Diseases in India

ladder markers and lambda DNA/Hind III
fragments.
Abstract:
Survival of Colletotrichum graminicola in the
soil at Burkina Faso
B. Traore and K.B. Kabore, Laboratoire de Recherches
du Service National de la Protection des
Vegetaux, B.P. 403, Bobo-Dioulasso, Burkina Faso.
Survival of sorghum anthracnose and stalk red
rot agent Colletotrichum graminicola on sandyloamy
soil near Bobo-Dioulasso, Burkina Faso,
was studied in 1987. Spores of the fungus were
counted in a sorghum field harvested and left
fallow in November 1986, and on another field
in 1987. The counts reveal that Colletotrichum
graminicola can survive in the soil for 9 months
following harvest, with 11 spores g -1 of soil. This
residue of Colletotrichum graminicola retained
pathogenicity and provoked stalk red rot of sorghum
upon artificial inoculation. Soil samples
from the cultivated field of 1987 shows that accumulation
of C. graminicola spores begins near
the last of July, at the end of tillering, and survive
until the end of the rainy season.
These results show the insufficient effect of seed
treatment and justify study of integrated pest management
in search of a method for complete control
of G graminicola in the sorghum production.
Abstract:
Identification of Striga germination stimulants
from sorghum-root exudate and their potential
significance in control of Striga.
L. Butler, Professor of Biochemistry, Purdue
University, West Lafayette, IN 47907, USA.
Sorghum root hairs exude a yellow oil containing
four structurally similar compounds that are
highly active as germination stimulants for
Striga hermonthica and Striga asiatica. The structure
of these compounds has been determined
and their biological activities are being characterized,
We have named these compounds sorgoleones.
They are hydroquinones, readily
oxidized to p- and o-benzoquinones with loss of
their capacity to stimulate the germination of
Striga. Their labile nature and their insolubility
in water ensure that only those Striga seeds located
very close to the host root will be stimulated
to germinate. Sorgoleones have other
biological activities which may benefit the sorghum
plant and thus prevent selection against
their protection under Striga stress. Striga apparently
utilizes sorgoleones as specific host-recognition
signals. Strategies for using analogs of
sorgoleones, in the absence of the host, as Striga
seed in infested fields, and as germination inhibitors
of Striga are proposed.
Abstract
Secondary sporulation of Sphacelia sorghi on
sorghum
D.E. Frederickson and P.G. Mantle, Department
of Biochemistry, Imperial College, London SW
2AZ/UK.
Etiology of the sorghum ergot disease pathogen,
Sphacelia sorghi McRae, becoming increasingly
important in hybrid seed production in southern
Africa, is not well understood. Collateral hosts
have not been identified. Evidence of a role for
sclerotia in the disease cycle, as with Claviceps
purpurea in temperate cereals and grasses, is
lacking. Current study of the disease cycle focuses
on sphacelial fructification and its associated
honeydew-containing conidia.
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