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Title: FITNESS AND AGGRESSIVENESS OF MEFENOXAM-RESISTANT AND -SENSITIVE ISOLATES OF PHYTOPHTHORA ERYTHROSEPTICA INFECTING POTATO

Author
item Porter, Lyndon
item MILLER, JEFFERY - UNIV OF IDAHO
item NOLTE, PHIL - UNIV OF IDAHO

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2005
Publication Date: 6/1/2005
Citation: Porter, L., Miller, J.S., Nolte, P. 2005. Fitness and aggressiveness of mefenoxam-resistant and -sensitive isolates of phytophthora erythroseptica infecting potato. Phytopathology. 95:S84.

Interpretive Summary:

Technical Abstract: Pink rot of potato is a major field and post-harvest problem in southeastern Idaho, particularly since mefenoxam-resistant isolates were detected in 1998. Fitness and aggressiveness of mefenoxam-resistant and –sensitive isolates of P. erythroseptica collected in 2001 to 2002 were determined. Zoospore production/mm of colony circumference was significantly greater for sensitive than resistant isolates, 14,191 and 9,959, respectively (P= 0.0109). Percentage of germinated zoospores at 20° Celsius was not significantly different for resistant and sensitive isolates (P= 0.9598). Incidence of pink rot tuber infection was significantly greater (P= 0.0162) for sensitive than for resistant isolates at temperatures of 10, 15, 20 and 25°C. Optimal temperature(s) for infection was 20°C for sensitive isolates and 15 and 20°C were co-optimal for resistant isolates. Rate of growth through tuber tissue was significantly different for resistant and sensitive isolates at 3.3°C but not at 7.2, 10, 15, 20, and 25°C, although growth of resistant isolates was numerically greater at all temperatures. Sexual fitness and aggressiveness of mefenoxam-resistant isolates may be greater than sensitive isolates, but sensitive isolates may be more asexually fit based on this and previously reported research.