New Disease Reports
New Disease Reports (2006) 14, 41.
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First report of Stagonospora foliicola on harding grass (Phalaris aquatica) in Argentina

M.V. Moreno* and A.E. Perelló

*fitopato@ceres.agro.unlp.edu.ar

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Accepted: 14 Nov 2006

Harding grass (Phalaris aquatica; syn P. tuberosa) is a perennial grass found throughout most of the pampas plains in Argentina. It is a particularly valuable plant, commonly used as a nutritious forage grass and also for hay and silage.

Since 2004 leaf symptoms have been observed on harding grass across the agricultural area of Buenos Aires Province. Oval, elongated, dark red lesions appeared on lower leaves. As lesions enlarged, they tended to become dark brown to reddish-brown blotches, usually with pointed ends and buff centres (Fig. 1). Pycnidia were observed between the leaf veins on dead leaves.

Isolates obtained from typical lesions on harding grass were identified as Stagonospora 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 dimensions of 50 pycniospores were 47.96 μm x 3.75 μm (Sprague, 1950; Fig. 2).

Pathogenicity tests were conducted in a greenhouse. Harding grass var. ‘El Gaucho’ was inoculated with a conidial suspension of S. foliicola (1 x 106 conidia per ml). Typical lesions developed on artificially inoculated leaves after 14 days and S. foliicola was consistently recovered. The isolate of S. foliicola from harding grass was deposited to the Centro de Investigaciones de Fitopatología Culture Collections, Universidad Nacional de La Plata, Argentina, as SFB0104.

S. foliicola has been reported in other countries on Agrostis, Calamagrostys, Cinna, Glyceria, Phalaris and Poa (Sprague, 1950; Zeiders, 1975; Farr et al., 1989). The disease is also known to occur on P. arundinacea (reed canary grass) in Australia, Europe and North America (Watson et al., 2000). Several diseases of Phalaris spp. are known but 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. The extent and importance of this disease in the Buenos Aires Province and the rest of Argentina is not yet known.

Figure1+
Figure 1: Lesions of Stagonospora foliicola on leaves of Phalaris aquatica var. ‘El Gaucho’
Figure 1: Lesions of Stagonospora foliicola on leaves of Phalaris aquatica var. ‘El Gaucho’
Figure2+
Figure 2: Pycnidiospores of Stagonospora foliicola from Phalaris aquatica var. ‘El Gaucho’ (400 x)
Figure 2: Pycnidiospores of Stagonospora foliicola from Phalaris aquatica var. ‘El Gaucho’ (400 x)

References

  1. Farr DF, Bills GF, Chamuris GP, Rossman AY, 1989. Fungi on Plants and Plant Products in the United States. St. Paul, Minnesota, USA: The American Phytopathological Society.
  2. Sprague R, 1950. Diseases of Cereals and Grasses in North America. New York, USA: The Ronald Press Co.
  3. Watson KW, McDonald WJ, Bourke CA, 2000. Phalaris Pastures, 2nd Edition. Orange, NSW, Australia: New South Wales Department of Agriculture: AgFacts No. P2.5.1
  4. Zeiders KE, 1975. Stagonospora foliicola a pathogen of reed canarygrass spray-irrigated with municipal sewage effluent. Plant Disease Reporter 59, 779-783.
This report was formally published in Plant Pathology

©2006 The Authors