Screening for resistance to Phytophthora fragariae var. rubi in Rubus germplasm at east malling

This paper summarizes experiments done at East Malling and describes screening young progenies and clonally-propagated genotypes, including new cultivars and trial selections, plus some Rubus species and early backcross derivatives. Progeny screening showed large differences in the percentage of seedlings which survived inoculation with Phytophthora fragariae var. rubi. Five summer and five primocane fruiting parents, which had been identified in earlier tests and classified from highly resistant to highly susceptible, were used to produce two half diallels which were screened for resistance. The results showed that 82-92% of the variation for resistance was additive. Screening clonally-propagated material over two or more years identified genotypes with strong or moderate resistance which could be used as parents.