C. L. Blomquist, California Department of Food and Agriculture, Sacramento 95832,
J. M. McKemy, USDA-APHIS PPQ NIS, Beltsville, MD 20705.
M. C. Aime, Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803;
R. W. Orsburn, Los Angeles County Agriculture Commissioner/Weights and Measures, Arcadia, CA 91006; and
S. A. Kinnee, California Department of Food and Agriculture, Sacramento 95832
Elongate, interveinal, hypophyllous lesions were observed on bamboo plants (Bambusa domestica) during an inspection of a plant shipment in November of 2006 in Los Angeles County, CA. Disease incidence was 100%. Minute uredinia were spaced at regular intervals within each lesion. Urediniospores were pale tan, echinulate, and 18 to 29 × 16 to 23 μm with 1- to 1.5-μm walls. The urediniospores were surrounded and partially covered by incurved pale-to-brownish yellow paraphyses 34 to 45 × 12 μm with walls that were primarily thickened apically and dorsally to 5 μm. Several telia were observed forming inside old uredinia. Telia were brownish black, forming a flabellar head of teliospores fused laterally and in chains of three to six cells. Teliospores were chestnut brown, cuboidal to oblong, and measured 10 to 12.5 × 12.5 to 25 μm. DNA sequence of the 28S large subunit nuclear ribosomal DNA was obtained using previously published methods (1). The sequence deposited in GenBank as Accession No. EF192212 matched sequence No. DQ354554 (1), Kweilingia divina from Costa Rica (1), with 100% identity. On the basis of morphological characteristics (2) and sequence information, the rust was identified as K. divina (Syd.) Buriticá (= Dasturella divina (Syd.) Mundk. & Khesw.), causal agent of bamboo rust. Bamboo rust is widespread in parts of Asia but has also been found in Africa, Colombia, Brazil, Central America (3), and Australia (4). The shipment was traced to a foliage plant producer in Hawaii where the disease was subsequently found in the environment on the four major Hawaiian Islands of Oahu, Hawaii, Kauai, and Maui. All 10 bamboo plants received by the nursery were located and destroyed. To the best of our knowledge, this is the first report of bamboo rust occurring in California.
References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) G. B. Cummins. Page 43 in: The Rust Fungi of Cereals, Grasses and Bamboos. Springer-Verlag, New York, 1971. (3) D. F. Farr et al. Fungal Databases, Systematic Mycology and Microbiology Laboratory. Online publication. ARS, USDA, year. (4) G. I. Johnson. Australas. Plant Pathol. 14:54, 1985.