2!»4 



PHRAGMIDIUM 



On Rosa canina, R. spinosissima, and many kinds of culti- 

 vated roses. Very common. Cae- 

 "ina-spores in May and June; 

 teleutospores, August — October. 

 (Fig. 222.) 



The teleutospores can germinate in 

 spring, and produce the crcoma (Jacky), 

 but they germinate with difficulty 

 M idler) ; 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 Kose- 

 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, Australia. 



5. Phragmidium fusiforme Schroter. 



Uredo ginguis var. Rosae-cdpvme DC. Flor. fr. ii. 235. 



P. fusiforme Schrot. Rostpilze Schles. p. 24. Fischer, Ured. Schweiz, 



p. 404, f. 283. Sacc. Syll. vii. 747. Sydow, Monogr. iii. 121. 

 Phragmidium Rosae-alpina< Wint. Pilze, p. 227. Plowr. Ured. p. 226. 



jEcidiospores. 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 — 30 x 15 — 20 /i. 



Fig. 222. Ph. disciflorum. a, 

 fficidiospore, on cultivated Rose ; 

 L, uredospore, and c, paraphyses, 

 on Dog Rose ; d, a small teleuto- 

 spore, on the same; e, a teleuto- 

 spore, on Burnet Rose ; all x 600. 



