ISHS Acta Horticulturae 619: XXVI International Horticultural Congress: Potatoes, Healthy Food for Humanity: International Developments in Breeding, Production, Protection and Utilization
THE PHYTOPHTHORA DISEASE COMPLEX OF POTATOES: ADDITIVE AND SYNERGISTIC INTERACTIONS BETWEEN P. INFESTANS AND P. ERYTHROSEPTICA IN TUBERS |
| Authors: | R.D. Peters, H.W. Platt, I.K. Macdonald, G. MacKenzie, K.A. MacIsaac, A.V. Sturz |
| Keywords: | Solanum tuberosum, pink rot, late blight |
| Abstract:
Late blight, caused by Phytophthora infestans, and pink rot, caused by P. erythroseptica, contribute to annual losses in stored potatoes. In surveys of potato storages in Prince Edward Island, Canada, both pathogens were commonly isolated from the same diseased tubers. To further examine the relationship between these oomycetes, experiments were established to assess disease incidence and severity on field-grown potato tubers (cvs. Norland, Shepody, Yukon Gold and Chieftain) and greenhouse-grown plants (cv. Green Mountain) inoculated with spore suspensions of P. infestans and P. erythroseptica, either singly or in combination. Inoculation of potato tubers and greenhouse-grown plants with sporangial suspensions of an isolate of the US-8 (A2) genotype of P. infestans caused significantly (P = 0.05) greater disease incidence and severity than inoculation with isolates of US-1 (A1) or US-11 (A1) genotypes, respectively. Co-inoculation of P. erythroseptica with P. infestans resulted in significantly (P = 0.05) greater necrosis than inoculation with either pathogen singly, particularly in the tubers of the cv. Norland. The incidence of tuber late blight was similar, whether inoculum of P. infestans was applied singly or in combination with P. erythroseptica. However, the incidence of tubers with pink rot was significantly (P = 0.05) increased in some cultivars when tubers were co-inoculated with P. erythroseptica and P. infestans. When P. infestans inoculum was applied to tubers one week prior to inoculation with P. erythroseptica, the frequency of tubers with pink rot was similar to that of a control where only sterile pond water had been applied prior to inoculation with P. erythroseptica. Our studies show that co-inoculation of P. infestans and P. erythroseptica increases tuber rot of potatoes, thereby exacerbating storage losses. | |
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