Breeding for resistance to Phytophthora root rot in red raspberries

Abstract

Phytophthora root rot, caused by Phytophthora fragariae van rubi, has become a major problem in raspberry growing also in Switzerland. Häberli Obst- und Beerenzentrum AG, a private nursery company, with its own breeding programmes in small fruits since 1983, has begun a programme with special respect to Phytophthora resistance in raspberries in 1989. In cooperation with the Institutes of Fruit-Growing and Phytopathology of the Technical University Munich at Freising-Weihenstephan a susceptibility test of the seedlings was set up. Over 3 years 22 different reciprocal crossings were made. The varieties‘Latham’,‘Winklers Sämling’ and‘Autumn Bliss’ were used as donors of resistance. These resistant varieties were crossed with several varieties with good fruit size, fruit quality, yield, but susceptiblity to Phytophthora root rot. In the 1989 test, where‘Latham’ and‘Winkler’s Sämling’ were used as donors of resistance, 106 of 601 seedlings survived the test (17.6%), 18 of which died after planting out. The total survival rate of the 1989 crossings was 14.2%. In the 1991 test with‘Autumn Bliss’ as donor of resistance 15 of 429 seedlings survived, the rate was 3.5%. All the surviving seedlings will be evaluated for their crop potential during the next years.