PUCCINIA 



309 



circumstances, and when it occurs early in the year the leaves 

 fall quite early in the season, and consequently the crop is 

 poor in quantity and quality. As a rule the rusts can only 

 attack young growing leaves, but in the present case I have 

 observed a plum-tree seriously attacked during the last week 

 in July. A considerable amount of confusion respecting the 



FIG. 90. Puccinia pruni. i, portion of diseased plum 

 leaf ; 2, teleutospore ; 3, paraphysis ; 4, lower cell and 

 portion of pedicel of a teleutospore, from which the 

 upper cell has broken away ; 5, uredospore. Fig. i 

 reduced, remainder highly mag. 



nature of the various kinds of reproductive bodies produced 

 by this species has existed until recently, when the matter 

 has been thoroughly worked out and put right by Professor 

 M'Alpine. 



Uredospores varying from almost globose to piriform, 

 smooth, apex conspicuously thickened, 18-36 x 14-18^; para- 

 physes numerous. 



Teleutospores formed of two almost globose, superposed 

 cells, the uppermost largest, brown, warted, pedicel hyaline, 

 elongated ; paraphyses numerous. 



Spray with dilute Bordeaux mixture at intervals, begin- 

 ning when the leaves are expanding. It is certain that the first 

 infection in spring is due to the presence of teleutospores, 

 hence all fallen diseased leaves should be dug in, or collected 

 and burned. 



M'Alpine, Ann. MycoL, 2, p. i (1904). 



Puccinia iridis (D. C.) is found on the leaves of many species 

 of iris. The uredospores form crowded pustules. Spores 

 elliptical or ovoid, rough, ochraceous, 20-35 x 16-26 /A. 



The teleutospores form long stripes, blackish, spores two- 

 celled, clavate, constricted at the septum, apex thickened, 

 30-35 x 14-22 fj.. No aecidium. 



Puccinia gentianae (Strauss) attacks various species of 

 cultivated gentian. The lower leaves are first attacked and 



