. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 294 PHBAGMIDIUM On Rosa canina, R, spinosissima, and many kinds of culti- vated roses. Very common. Cse- oma-spores in May and June; teleutospores, August—October. (Fig. 222.) The teleutospores can germinate in spring, and produce the cseoma (Jacky), but they germinate with difficulty (Mtiller); the parasite is propagated chiefly by the mycelium of the cseoma- stage, which passes the winter in the branches and in spring bursts out into wide-spreading spore-beds. These at- tack and destroy the buds ; afterwards
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 294 PHBAGMIDIUM On Rosa canina, R, spinosissima, and many kinds of culti- vated roses. Very common. Cse- oma-spores in May and June; teleutospores, August—October. (Fig. 222.) The teleutospores can germinate in spring, and produce the cseoma (Jacky), but they germinate with difficulty (Mtiller); the parasite is propagated chiefly by the mycelium of the cseoma- stage, which passes the winter in the branches and in spring bursts out into wide-spreading spore-beds. These at- tack and destroy the buds ; afterwards the uredo- and teleutospores appear on the leaves, with localised mycelium. The infested branches are often swollen and deformed. To keep the disease under control, all teleutospore-bearing leaves and the branches which are permeated by the mycelium should be collected and burnt, and the plant may be sprayed, during the winter, with copper sulphate solution. It is noteworthy that this fungus occurs in North America only on cul- tivated roses; the indigenous Rose- Phragmidia are all different species. It has been introduced, probably by. cuttings, also into Australia and other parts of the world. Distribution : Europe, Asia Minor, Persia, Africa, North America, South America, Fig. 222. Ph. disciflorum. a, seoidiospore, on cultivated Rose ; b, uredospore, andc, paraphyses, on Dog Rose; d, a small teleuto- spore, on the same; e, a teleuto- spore, on Burnet Rose; all x 600. 5. Phragmidium fusiforme Schroter. Uredo pinguis var. Rosae-alpinae DC. Flor. fr. ii. 235. P. fusiforme Schrot. Eostpilze Schles. p. 24. Fischer, Ured. Schweiz, p. 404, t 283. Saoc. Syll. vii. 747. Sydow, Monogr. iii. 121. Phragmidium Rosae-alpinae Wint. Pilze, p. 227. Plowr. Ured. p. 226. ^cidiospores. Sori on the petioles, nerves and fruits, similar to those of P. disciflorum, but not so extensive; on the leaves, punctiform and surrounded by hyaline clavate para- physes; spores echinulate, 17—3
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