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First Report of Garlic Rust Caused by Puccinia allii in Oregon

In June of 2000, garlic rust caused by Puccinia allii F. Rudolphi was detected in a single commercial garlic field (Allium sativum L.) in the Willamette Valley of western Oregon. To our knowledge, this is the first report of P. allii in Oregon. The pathogen was present in low levels throughout the majority of the garlic field with little apparent effect; however, several 10 to 20 m wide lenses of severely damaged plants were observed. In the lenses, the plants were stunted and the outer leaves were prematurely senescent. Uredia were abundant and irregularly scattered on the leaves and gave the heavily infected plants an orange cast. The field was resurveyed in August and telia and uredia were collected. Urediospores were ellipsoid and measured 29 to 35 × 20 to 26 μm. Urediospore walls were generally hyaline, 1 to 2 μm thick and echinulate. Telia were black, oval to elongate, and non-erumpent to slightly erumpent. Teliospores were predominantly two-celled and measured 40 to 62 × 19 to 30 μm. The cap cells were angular to acuminate and irregular. Pedicels were generally shorter than the length of the spore. These characteristics are consistent with published descriptions of P. allii (1). P. allii was not detected in any of the 103 garlic or 113 onion seed fields enrolled in the state's phytosanitary certification programs during 2000.

References: (1) G. F. Laundon and J. M. Waterson. CMI Descr. Pathog. Fungi Bact. No. 52, 1965.