| Autor: |
Kennedy, Diana M., Duncan, James M., Dugard, Patricia I., Topham, Pauline H. |
| Předmět: |
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| Zdroj: |
Plant Pathology; Sep86, Vol. 35 Issue 3, p344-354, 11p |
| Abstrakt: |
A system for scoring the virulence of isolates of Phytophthora fragariae based on a scale of root rot from O (no symptoms) to 5 (75-100% roots rotted) on a series of strawberry cultivars is described. Thirty-two single-zoospore isolates from one field site were compared by subjecting their root rot scores to cluster analysis and this grouped them into two major clusters equivalent to physiologic races B66-3 and B66-11. Different sub-clusters of isolates of race B66-11 produced different degrees of rotting on the same hosts. Apart from differences in virulence between the sub-clusters there was some evidence for difference in aggressiveness between isolates within sub-clusters. Increasing inoculum concentration by over 300-fold increased rotting by c. 25% but did not alter the rankings of different isolate/host combinations. Repeated passage of isolates through cultivars of differing susceptibilities did not affect their pathogenicity. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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