First report of Stagonospora foliicola on harding grass (Phalaris aquatica) in Argentina

MORENO, V.; PERELLÓ, A.

PLANT PATHOLOGY

Lugar: USA; Año: 2006 vol. 07/0 p. 1 - 2

0032-0862

First report of Stagonospora foliicola on Phalaris aquatica (Phalaris tuberosa) leaves in Argentina. M. V.  Moreno1,2* and A. E. Perelló1,2   1 Centro de Investigaciones de Fitopatología (CIDEFI), Facultad de Ciencias Agrarias y Forestales de la Universidad Nacional de La Plata. Calle 60 y 119 (1900) La Plata, Pcia. de Buenos Aires, Argentina. CC 31. 2Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) *morevir@yahoo.com.ar  ; fitopato@ceres.agro.unlp.edu.ar   Harding grass (Phalaris aquatica) is a perennial grass spread throughout most of the pampas plains in Argentina. It is a particularly valuable plant which is commonly seeded as a nutritious forage grass and also used for hay and silage.   Since 2004 leaves symptoms have been observed in plants across the agricultural area of Buenos Aires Province. In the field, oval, elongated, vinaceous lesions appear on lower leaves; as they enlarged they tended to become dark brown to reddish-brown blotches, usually with pointed ends and buff centers (Figure 1). Pycnidia between the leaf veins were observed on dead leaves.   All isolates obtained were identified as S. foliicola (Bresadola.) Bubák. Pycnidia were globose-aplanate, gray to light brown and ostiolate. Conidia were hyaline, thin-cylindrical, straight to gently curved, with six to eight septa per spore. The average of 50 pycniospores was  47.96 μ x 3.75 μ   (Sprague, 1950) . (Figure 2)   Pathogenicity tests were conducted in the greenhouse. Harding grass var. “el gaucho” was inoculated with a conidial suspension (1 x 106conidia per ml). The plants of harding grass artificially inoculated were susceptible to infection by S. foliicola, which was recovered from lesions.   The isolate of S. foliicola was deposited to the Centro de Investigaciones de Fitopatología Culture Collections, Universidad Nacional de La Plata, Argentina, as SFB0104.   S. foliicola has been reported on: Agrostis, Calamagrostys, Cinna, Glyceria, Phalaris and Poa  (Farr et al.,1989; Zeiders, 1975; Sprague,  1950; Watson et al.,  2000) . The extent and importance of this disease is not known in others parts of Argentina. The disease is known to occur on P. arundinacea (reed canary grass). Several parasitic diseases of Phalaris spp. are known but most of them rarely cause severe damage. (Watson et al., 2000).    This is the first published record of S. foliicola on P. aquatica in Argentina and on any other hosts in this country.   References   Farr DF.  Bills GF. Chamuris GP. Rossman AY. 1989. Fungi on plants and plant products in the United States. The American Phytopathological Society 1252 pp. Sprague R. 1950. Diseases of cereals and grasses in North America. The Ronald Press Co., New York, 538pp. Watson KW. Mc Donald WJ. Bourke CA. 2000. Phalaris pastures. AGFACTS, NSW Agriculture, 2º ed. 32pp. . Zeiders KE. 1975. Stagonospora foliicola a pathogen of reed canarygrass spray-irrigated with municipal sewage effluent. Plant  Disease Reporter 59. 779-783.   Figure 1. Lesions of Stagonospora foliicola on Phalaris aquatica var. “El Gaucho” leaves under field conditions. Figure 2. Pycnidiospores of Stagonospora foliicola from Phalaris aquatica var. “El Gaucho”  (400 x).