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Disease Note First Report of Sclerotium rolfsii on Wheat in Western Australia. M. M. Dewan, Soil Science and Plant Nutrition, School of Agriculture, The University of Western Australia, Nedlands 6009. K. Sivasithamparam, Soil Science and Plant Nutrition, School of Agriculture, The University of Western Australia, Nedlands 6009. Plant Dis. 71:1146. Accepted for publication 31 August 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-1146E. Sclerotium rolfsii Sacco was isolated from roots of wheat (Triticum
aestivum L.) and ryegrass (Lolium rigidum Gaudich.) from a wheat
field at Dandaragan in the Western Australian grain belt in October
1986 at milky-ripe (0.2 and 0.4%, respectively, of all fungi isolated) and
at ripe-for-cutting (8.0 and 5.0%, respectively) stages. Wheat (cv.
Gamenya) sowed in June 1987 showed 12% preemergence and
postemergence death of seedlings. Mycelia and sclerotia of the fungus
were associated with the dead seedlings (1). Pathogenicity tests at 20 ± 2
C in sterile soil with 1% inoculum wjw resulted in severe preemergence
and postemergence death of wheat (61.1%) and ryegrass (62.0%). Other
hosts showing disease were bromegrass (Bromus diandrus Roth),
75.6%; barley (Hordeum vulgare L.), 54.8%; subterranean clover
(Trifolium subterraneum L.), 33.3%; lupin (Lupinus angustifolius L.),
82.4%; and oats (Avena sativa L.), 63.8%. These crops are grown in
rotation with wheat and may serve to increase the soil population levels
of S. rolfsii. |