SCREENING FOR RESISTANCE TO PHYTOPHTHORA ROOT ROT IN RASPBERRIES: IDENTIFYING NEW SOURCES OF RESISTANCE

C. Kempler, A.M. Muehlchen , T.A. Forge
Phytophthora root rot caused by Phytophthora rubi ((Wilcox & Duncan) Man in’t Veld) is a disease that limits the production and longevity of raspberry fields throughout the world. Natural plant resistance to the pathogen is available in some cultivars and in some related species of Rubus, and plant breeders are working to incorporate this resistance into commercially acceptable cultivars. Because the disease can be patchy and slow to appear in the field, a more rapid and standardized method of screening selections in the greenhouse was developed at the Agriculture and Agri-Food Canada Research Centre at Agassiz, British Columbia. P. rubi was isolated from two raspberry fields exhibiting root rot symptoms, and these isolates were used in the screens. Test plants were raised in tissue culture and inoculated with macerated hyphae of the pathogen, in a semi-hydroponic system in the green¬house. After incubation under flooded conditions, roots were rated for root rot severity. The process is relatively rapid and has consistently discriminated known susceptible cultivars from known resistant cultivars. The screenings have identified new sources of resistance in clones that are derivatives of R. strigosus, R. niveus, R. lasiostylus and R. innominatus. A new source of resistance has also been identified in a clone of the Korean black raspberry R. coreanus.
Kempler, C., Muehlchen , A.M. and Forge, T.A. (2012). SCREENING FOR RESISTANCE TO PHYTOPHTHORA ROOT ROT IN RASPBERRIES: IDENTIFYING NEW SOURCES OF RESISTANCE. Acta Hortic. 926, 59-64
DOI: 10.17660/ActaHortic.2012.926.6
https://doi.org/10.17660/ActaHortic.2012.926.6
Rubus sp., Phytophthora rubi, plant breeding, disease evaluation
English

Acta Horticulturae