Infection of Chrysanthemum Flowers by White Rust ( Puccinia horiana Henn.)

SUMMARY A description is given of white rust infection of the florets of cv. Yellow Delaware which is believed to be the first record of flower infection by this rust. Microscopic development of the fungus in the ray florets is described in Yellow Delaware, a cultivar susceptible to leaf infection, and in Apricot Princess Anne, a cultivar which has shown no leaf symptoms in tests in England. In the latter cultivar, fungal development was limited and associated with necrotic flecking.