Screening Azalea Cultivars for Resistance to Phytophthora cinnamomi Root Rot
D. M. Benson and B. I. Daughtry
North Carolina State University, Raleigh, NC
Proceed. of So. Nurserymen Assoc. Res. Conf. 1979. 24:125.
Liners growing in sand: soil: peat at pH 5.5 were inoculated with Phytophthora cinnamomi. A root rot rating for Phytophthora root rot was assigned 4 months after inoculation with 1 = healthy roots, 2 = fine roots necrotic, 3 = coarse roots necrotic, 4 = crown rot and 5 = dead plants. Their results were as follows: Back Acres 2.7, Gable 2.9, Glenn Dale 2.6, Indian 2.4, Kurume 3.0, Pericat 2.5, Rutherford 2.4, Satsuki 2.7, Whitewater 2.6, and the newly released NCSU hybrids 4.2. Cultivars most tolerant of root rot were Corrine Murrah, Fakin and Formosa. One species tested Rhododendron poukhanense, Leveille had a rating of 1.6. Future research to find resistance should be concentrated at the species level.