| Abstrakt: |
The interactions of four potato cultivars, with three isolates ofPhytophthora infestanswere assessed in different environments and in different years. Preliminary tests with these cultivars and isolates were conducted in Toluca, Mexico, and Freeville, New York, U.S.A. in 1986 and 1987. Although data were available from only one year for cultivar Alpha, this cultivar had a dramatically different resistance ranking in Toluca, than that in Freeville — a result consistent with previous observations. The difference in resistance between two other cultivars also changed with site, but less dramatically and did not cause a change in resistance ranking. The resistance of the fourth cultivar appeared to be relatively unaffected by change in site. In both sites, all isolates ranked all cultivars in the same order. Although aggressiveness was slightly different in different locations and on different cultivars, variations were small and there were no consistent trends (consistent over all trials) concerning isolate aggressiveness. Thus, changes in location appeared to have different effects on the different cultivars but little or no effect on the isolates used. |
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