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| Department of Agriculture, Aquaculture and Fisheries |
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Abstract: Pink rot of potatoes caused by Phytophthora erythroseptica is known to infect roots, stolons, tubers and basal stems of potato
(Solanum tuberosum). Potato leaves and stems do not often show symptoms except when extensive infection of underground plant parts results in wilt,
chlorosis, and necrosis. This is the first study to investigate the spread of P. erythroseptica in above-ground tissues using both traditional
isolation and PCR methods originally developed to detect the pathogen in tubers. Phytophthora erythroseptica was detected in 66% of leaf and stem
tissue samples originated from artificially-inoculated and naturally-infected tubers of 'Yukon Gold' and 'Shepody' by PCR methods. However, it was
recovered in pure cultures only from 38% of stem and leaf tissue samples. Pathogen was also detected in leaf and stem tissues and aerial tubers of
plantlets grown in potting mixtures infested with P. erythroseptica. Pure cultures of P. erythroseptica obtained from stem and leaf tissues, together
with the 95% of the detection with the real-time PCR assay and 45% with the conventional PCR assay confirmed the viability of the pathogen in
above-ground potato tissues. Furthermore, the pathogen was detected in progeny tubers and stolons produced by the infected potato plants. Phytophthora
erythroseptica was also detected in a few samples of debris taken from naturally senesced above-ground potato tissue after harvest.