Minnesota Plant Diseases. xxiii 



Fig. 198. Downy mildew of grape. Spores and spore-bearing threads. 



Highly magnified. After Millardet 370 



Fig. 199. Leaf rust of roses. The cluster-cup stage on the stems and 



leaves. Photograph by H. Cuzner 374 



Fig. 200. Leaf rust of roses. Stem with groups of cluster-cups. Origi- 

 nal 375 



Fig. 201. Leaf rust of roses. Variously magnified. After Massee 376 



Fig. 202, Powdery mildew of lilac. Original 377 



Fig. 203. Powdery mildew of roses. A leaf of the rose attacked by the 



disease. After Clinton 378 



Fig. 204. Powdery mildew of roses, showing the superficial mycelium 



and summer spores on the leaves. After Tulasne 379 



Fig. 205. Golden-rod rust. Original 388 



Fig. 206. Sunflower rust. Original 389 



Fig. 207. The stem rust of the cowberry. Highly magnified. After 



Hartig 390 



Fig. 208. Rust of wild sarsaparilla. Original 391 



Fig. 209. Mint rust. Original 393 



Pig. 210. Powdery mildew of composites, on the leaf of the great rag- 

 weed. Original 396 



Fig. 211. Gall fungus on the wild peanut. Original 398 



