Leaf and Stem Spot Caused by Ramularia sphaeroidea on Purple and Lana Woollypod Vetch (Vicia spp.) Cover Crops in California

Autor: S. T. Koike, Johannes Z. Groenewald, Pedro W. Crous, Richard Smith
Rok vydání: 2004
Předmět:
Zdroj: Plant Disease. 88:221-221
ISSN: 1943-7692
0191-2917
DOI: 10.1094/pdis.2004.88.2.221b
Popis: Vetches (Vicia spp.) are planted alone or in combination with other plants as cover crops in vegetable production areas of California. December 2001 through February 2003, purple (V. benghalensis) and lana woollypod (V. villosa subsp. varia) vetches in the Salinas Valley (Monterey County) developed a foliar disease. Symptoms were small (≤5 mm in diameter), circular to oblong, purple brown-to-red brown spots that were visible from the adaxial and abaxial leaf sides, and occurred lower in the plant canopy. White sporulation was visible in the spot centers. Stems were infected and had elongated, irregularly shaped, brown lesions that were 5 conidia per ml) onto direct-seeded, 8-week-old, potted purple and lana woollypod vetch (12 plants each). Plants were kept in a dew chamber for 48 h and maintained in a greenhouse (23 to 25°C). After 7 to 10 days, all plants developed the characteristic leaf spots and stem lesions, and R. sphaeroidea was reisolated from such symptoms. Plants treated with only water did not develop symptoms. However, because disease incidence on test plants was low, inoculum was also prepared in water amended with 1.0 ppm of Tween 20. Four pots each of purple and lana woollypod vetch were sprayed with amended or nonamended inocula, and plants were handled as described. After 10 days, plants inoculated with Tween 20 amended inoculum had significantly higher disease incidence and severity (purple = 83% of leaflets infected with a mean of 3.4 spots per leaflet; lana = 83% infected with a mean of 3.2 spots) than did plants inoculated with water-only conidial suspensions (purple = 27% and a mean of 0.4 spots; lana = 38% and a mean of 0.6 spots). Finally, two other vetches used in the Salinas Valley were inoculated with the two suspensions. After 2 weeks, common (V. sativa) and languedoc (V. sativa ‘Languedoc’) vetch showed no symptoms, and control plants of purple and lana vetch developed disease. All inoculation tests were repeated, and results were similar. To our knowledge, this is the first report of R. sphaeroidea as a pathogen of purple and lana woollypod vetches in California. Reference: (1) U. Braun. A Monograph of Cercosporella, Ramularia, and Allied Genera (Phytopathogenic Hyphomycetes) Vol. 2. IHW-Verlag, Eching, Germany, 1998.
Databáze: OpenAIRE
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