Occurrence and epidemiological aspects of potato silver scurf in California
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2004-12
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Resumo
A new potato tuber disease has been observed in the Tulelake
region, California, USA, since 1995, with tuber symptoms suggestive
of silver scurf disease (Helminthosporium solani). In this work we
isolated, identified and demonstrated the nature of the causal agent
of this potato disease in California. In addition, the distribution of
H. solani in potato fields and the inoculum potential at harvest time
were investigated. Disease progress and H. solani spore populations
were also characterised under commercial storage conditions. The
main fungal genera associated with potato tubers in storage were
Helminthosporium solani, Colletotrichum sp., Fusarium sp., and
Rhizoctonia sp. The results of Koch’s postulates indicated that H.
solani is responsible for the outbreak of silver scurf in the Tulelake
region. In a disease survey in three commercial potato fields naturally
infested, H. solani infections occurred in all fields. However, the
extension of the infections differed significantly between the fields.
During potato storage, silver scurf usually increased over time. The
percentage of the tuber surface covered by silver scurf varied from
3.5% up to 35.5% during the storage period. The number of H. solani
lesions per tuber also progressively increased from 6% up to 35%,
six months after storage. H. solani spore populations also increased
over time in all studied potato stores; nevertheless, they followed no
consistent pattern, exhibiting multiple and variable peaks of increase
and reduction during the period of storage.
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Solanum tuberosum, Spore population, Helminthosporium solani, Potato tuber disease, Disease progress, Post-harvest disease, Solanum tuberosum, Doença de tubérculo, Helminthosporium solani, População de esporos, Progresso de doenças, Doença de pós-colheita
Citação
CUNHA, Marcos G.; RIZZO, David M. Occurrence and epidemiological aspects of potato silver scurf in California. Horticultura Brasileira, Brasília, v. 22, n. 4, p. 690-695, Oct./Dec. 2004