Photo 3. Sporeballs or sporosori of powdery scab, Spongospora subterranea, which germinate to produce swimming zoospores.
Spongospora subterranea f.sp. subterranea. It is a member of the family Plasmodiophoraceae, the same family as that of Plasmodiophora brassicae, the cause of club root of brassicas (see Fact Sheet no. 283). Like Plasmodiophora brassicae, powdery scab belongs to a group called rhizaria in the Kingdom Protista; they are related to slime moulds.
AUTHOR Grahame Jackson
Information from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, Tony Cooke, Susan House. CSIRO Publishing; and from Powdery scab (2016) Wikipedia. (https://en.wikipedia.org/wiki/Powdery_scab). Photos 1-3 Sandra Jensen, Cornell University, Bugwood.org. Diagram Steven B Johnson (2002) Bulletin No. 2436, Powdery Scab of Potatoes. The University of Maine. (https://extension.umaine.edu/publications/2436e/).
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.
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