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Metalaxyl sensitivity of isolates of Phytophthora erythroseptica in Prince Edward Island
Author(s) -
Peters R. D.,
Sturz A. V.,
Matheson B. G.,
Arsenault W. J.,
Malone A.
Publication year - 2001
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1046/j.1365-3059.2001.00566.x
Subject(s) - metalaxyl , biology , phytophthora infestans , phycomycetes , fungicide , solanaceae , pathogen , botany , horticulture , inoculation , microbiology and biotechnology , blight , genetics , gene
Isolates of Phytophthora erythroseptica , causal agent of pink rot of potato, were obtained from diseased tubers collected in Prince Edward Island (PEI), Canada. In an in vitro assay of field and single‐zoospore isolates, all isolates of the pathogen from PEI were sensitive to metalaxyl (EC 50 < 0·5 µ g mL −1 ), unlike moderately or highly resistant reference isolates obtained from Maine, USA. Allozyme‐banding patterns at the glucose‐6‐phosphate isomerase ( Gpi ) locus were identical (91/91) for all isolates of P. erythroseptica examined from PEI and Maine, but could be used to distinguish isolates of P. erythroseptica from local isolates of Phytophthora infestans . Inoculation of potato tubers from plants treated with foliar applications of metalaxyl in the field indicated that compounds inhibitory to metalaxyl‐sensitive isolates of P. erythroseptica were present in the periderm, even after 4 months' storage. By contrast, moderately or highly resistant isolates of the pathogen caused significantly ( P ≤ 0·05) more disease than sensitive isolates in tubers from plants treated with metalaxyl. The effectiveness of metalaxyl in controlling pink rot in a particular region will depend on resistance levels of local populations of P. erythroseptica . Preventing the development and spread of resistant strains of P. erythroseptica will be critical in maintaining metalaxyl as an effective chemical for control of this pathogen.