Scab of Wheat and Barley in Southern Idaho and Evaluation of Seed Treatments for Eradication of Fusarium spp.. Laura Mihuta- Grimm, Research Associate, Division of Plant Pathology, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Research and Extension Center, Route 1, Kimberly 83341. Robert L. Forster, Professor, Division of Plant Pathology, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Research and Extension Center, Route 1, Kimberly 83341. Plant Dis. 73:769-771. Accepted for publication 5 January 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0769.

In 1982 and 1984, unusual, prolonged rainy and cloudy weather during anthesis promoted scab epidemics in sprinkler-irrigated wheat and barley fields in south central and eastern Idaho. Virtually all plants were diseased in affected fields, and estimated yield losses were as high as 50% in some fields. Rill-irrigated fields in the same area had little or no scab, thus indicating the necessity of favorable weather conditions and sprinkler irrigation for scab epidemics to occur in this semiarid region. Fusarium culmorum was most frequently isolated from harvested scab-infested grain, which strongly implicates this species as the principal scab pathogen in this region. Other Fusarium spp. isolated were F. acuminatum, F. avenaceum, F. graminearum, and F. equiseti. Koch’s postulates were completed for all of these species, corroborating previous reports indicating that the disease is caused by several Fusarium spp. Fungicidal seed treatments were evaluated for eradication of seedborne Fusarium and prevention of the seed decay and seedling blight phases of the disease; levels of seedborne Fusarium were substantially reduced, but this did not result in greater seedling emergence or better stands in a field trial in 1986.

Keyword(s): fungicides, Hordeum vulgare, rill irrigation, Triticum aestivum.