39 2 Minnesota Plant Diseases. 



Rust of Indian turnip [Uromyces caladii (Schw.) Far/.]. 

 This rust is very abundant in Minnesota. It is found in the 

 wild state, chiefly on Indian turnip, but is also known on the 

 dragon root and on other cultivated aroids. All three rust 

 stages grow upon the same host plant. The cluster cups ap- 

 pear in the spring and are evenly distributed over the lower sur- 

 face of the leaf. In early summer, the summer spores are pro- 

 duced in small, round, yellowish pustules and these are followed 

 by the winter spores. The latter are brownish and single- 

 celled. The mycelium is capable of wintering over in the swol- 

 len, underground, bulbous stem, so that a plant, once infected, 

 cannot be rid of the fungus. Infected cultivated plants must 

 therefore be destroyed as soon as the disease appears. 



Cedar apple of red cedar (Gymnosporangium macro pus Lk. 

 and Gymnosporangium globosum Far/.). See Leaf-rust of 

 Apples and Pears. Diseases of Orchards and Vineyards. 



Leaf rust of plums (Puccinia pruni Pers.). On many wild 

 cherries. See Diseases of Orchard Plants. 



Leaf rust of juneberry. See Birds-Nest Rust of Red Ce- 

 dar. Diseases of Orchards and Vineyards. 



Club rust of juniper [Gymnosporangium davariaeforme 

 (Jcq.) Rees.]. See Diseases of Orchards and Vineyards. 



Rust of mints (Puccinia menthae Pers.). See Diseases of 

 Garden Plants. 



Rust of violets [Puccinia violae (Schum.) D. C.]. See Dis- 

 eases of Greenhouse Plants. 



Rust of rose leaf [Phragmidium subcorticium (Schrk.) 

 Wint.~\. See Diseases of Greenhouses and Ornamental Plants. 



Smut of anemone [Urocystis anemones (P.) Schroet.']. This 

 is not an uncommon smut upon a great number of our spring 

 wildflowers of the crowfoot family. It is often found upon the 

 liver-leafed anemone or hepatica. The smut forms upon the 

 leaves, stems or petioles and produces large, black, sack-like 

 pustules of spores. The pustule is at first covered with a thin, 

 greyish membrane, which later breaks and releases the spores 

 in a powder. The spores are not formed and liberated singly 

 as in ordinary powdery smuts, but are grouped together into 

 small spore-balls. Each ball consists of a number of spores of 

 two kinds: there are one to several large, central spores sur- 



