The Resistance of Various Cultivars and Species of Chrysanthemum to White Rust ( Puccinia horiana Henn.)

SUMMARY Thirty‐seven cultivars of the florists' chrysanthemum remained uninfected under experimental conditions favouring infection of the susceptible cultivars Golden, Yellow and White Favourite and Yellow Delaware. Although reported in the literature as susceptible, a number of cultivars, including Princess Anne and Brietner, remained uninfected. Twenty‐six other Chrysanthemum species, and some of their cultivars, were also tested and of these only C. yezoense , a number of the hybrids of C. indicum and C. koreanum and also, to a lesser extent, C. nipponicum and C. uliginosum became infected.