Powdery scab situation
Powdery scab of potatoes, caused by Spongospora subterranea (Wallr.) Lagerheim f. sp. subterranea_ Tomlinson [Ss], is important worldwide because of its effect on tuber quality and as the vector of Potato mop-top pomovirus. Scab-like lesions have been observed on potato in Costa Rica (1), but the presence of the pathogen remained unconfirmed.
In 2001, powdery scab was observed in a field and a greenhouse in the high elevation zone of the main potato-producing area of Costa Rica and on commercial potatoes obtained at a farmers' market. The presence of spore balls or cystosori with a honey-comb-like structure under light microscopy confirmed the identity of S. subterranea. Its identity was also confirmed by ELISA using monoclonal antibodies specific for Ss (BioReba Ag, Reinach, Switzerland). Pathogenicity of Ss was confirmed by bioassay on tomato plants grown in nutrient solution culture (2). Tomato (Lycopersicon esculenta) cv. Supermarmande were grown from seed in pots filled with quartz and watered with nutrient solution. After 3 weeks, the roots were trimmed to 60 mm, and plants were transferred to a nutrient solution for further growth. After 1 week, tomato seedlings were inoculated by replacing the nutrient solution with nutrient solution containing cystosori (20 mg/liter, wt/vol). Zoosporangia of Ss were observed in root hairs and epidermal cells of seedlings 2 weeks after inoculation.
To our knowledge, this is the first report that confirms the presence of Sss on potato in Costa Rica.
M. Montero-Astua and V.Vasquez, Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica (UCR); and C. Rivera, CIBCM and Facultad de Microbiologia, UCR. Plant Dis. 86:1273, 2002; published on-line as D-2002-0826-01N, 2002. Accepted for publication 12 Aug 2002.
M. Montero-Astua, V. Vasquez, W.W. Turecheck, U. Merz and C. Rivera, 2008. Incidence, distribution and association of Spongospora subterranea and Potato mop-top virus in Costa Rica. Plant Dis. 92, 1171-1176.
Research See above and more in the references.
Contact address:
Mauricio Montero Astua
Centro de Investigación en Biología Celular y Molecular (CIBCM)
Universidad de Costa Rica
San Pedro
Costa Rica
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Last update: January, 2025