Author
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Oneill, Nichole |
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Farr, David |
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Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/8/1996 Publication Date: N/A Citation: N/A Interpretive Summary: A new disease was discovered on varieties of the ornamental grass Miscanthus growing in Maryland and Virginia. During 1993, 1994, and 1995, the leaf blight disease caused severe blighting on residential landscape plants, nursery container stock, and commercial stock plantings. The cause of the disease was identified as a fungus in the genus Stagonospora sp. and its sexual stage Leptosphaeria sp. In growth chamber tests, the fungus was highly virulent to varieties of sugarcane and Miscanthus. The disease and causal agent was similar to Sugarcane Leaf Blight, a serious sugarcane disease in Taiwan and the Far East. Direct comparisons the Miscanthus fungus with sugarcane leaf blight disease pathogens must be made before a species identification of the Miscanthus fungus can be made. Sugarcane leaf blight and Miscanthus blight have not been reported from the United States, and U.S. sugarcane lines have not been screened for resistance to this disease. This information is important for sugarcane growers, nurseries and scientists working to protect these crops from diseases. Technical Abstract: Severe leafspot and leaf blight symptoms were observed on four varieties of the ornamental grass Miscanthus sinensis during the late summer and fall of 1993, 1994, and 1995 in Maryland. Symptoms appeared on residential landscape plants, nursery container stock, and field row plantings for stock increase. The disease is characterized by reddish brown spots to oval streaks on leaves and sheaths. Leaf margins, leaf tips, and older leaves become necrotic. Younger plants become completely necrotic. The cause of the disease was investigated. A fungus was readily isolated in pure culture from affected plant parts. Pycnidia and conidia of Stagonospora and perithecia and ascospores of Leptosphaeria were produced and isolated from naturally infected necrotic Miscanthus leaves. The fungus is homothallic, and both the anamorphic and teleomorphic states were produced on inoculated Miscanthus and sugar cane foliage, and on autoclaved sugarcane leaves. The anamorph is morphologically distinct from other Stagonospora pathogens described from sugarcane, but the teliomorph is similar to Leptosphaeria taiwanensis (anamorph of S. tainanensis), cause of sugarcane leaf blight. At this time taxonomic uncertainties in the literature prevent species designations for the Miscanthus pathogen. In growth chamber inoculations, conidia produced by the Miscanthus fungus and by S. tainanensis from sugarcane caused similar, severe blight symptoms on four Miscanthus varieties and six sugarcane accessions. Sugarcane leaf blight is a serious disease in Taiwan, and has not been reported in the U.S. The name proposed for the new disease on Miscanthus is Miscanthus blight, caused by Leptosphaeria sp. and its conidial state Stagonospora sp. |
