GRASSES OP IOWA. 257 



countries by Sorauer,* Frank t and others. It also occurs in 

 Australia where it is said to do much damage. It was first 

 found in this country by Underwood J and Cook, who distributed 

 the fungus, and later in Connecticut by Thaxter.§ It is not 

 nearly so common in Europe as other cereal smuts and to my 

 knowledge has never teen found in Iowa. 



It is stated that between the years of 1850 and 1860 it was 

 so destructive in parts of South Australia that in some locali- 

 lities cultivated rye sustained a loss of 66 per cent. Like 

 timothy smut it attacks the leaves, sheaths, stem, and inflores- 

 cence, but generally it is found on the leaves and sheaths. It 

 makes its appearance about the middle of May and continues 

 through June. It is characterized by lead colored patches 

 which are arranged in parallel rows along the veins. The 

 epidermis which covers the sori soon becomes ruptured and 

 exposes the powdery spores, and like timothy smut, the 

 leaf is soon torn up into brown shreds The spores differ very 

 materially from any we have thus far considered. They are 

 arranged in clusters made up of two kinds of cells. The central 

 ones are darker ia color, and are capable of germination; the 

 surrounding cells are lighter in co]or and do not germinate. 

 The Urocystis spores do not germinate very readily. The pro- 

 mycelium bears the sporidia at the end. The fungus enters its 

 host through the very young leaves close to the seed. Wolff 

 states that the fungus cannot enter later. Iq eight or nine 

 weeks rye, inoculated with sporidia, produced spores in the 

 seventh or eighth leaf. When the sporidia come in contact 

 with the leaf they attach themselves very closely, pen trate 

 the cuticle of the epidermal cell, growing crosswise through 

 the young seedling and then passes from the inner epidermal 

 cell of one leaf t3 the outer of another. The mycelium when 

 once in the interior of the plant grows in the intercellular 

 spaces, sending haustoria into the cells. 



WILD RYE SMUT. 



This smut, Urocystis agropyri (Preuss), Schr., occurs on sev- 

 eral grasses in Europe and the United States. || 



♦Pflanzenkrankhelten. 190. 

 tKrankhelten d. Pflanzen. 121 (Ed. 3). 

 ik Century of Illustrative Fung. No. 57. 1889. 

 §Rep. Coun. Agrl. E.xp. Sta. 1899: 143. pi. 2. f. 9-W. 

 liSaccardo. Syll. Fuag. 7: 516. 

 Farlow and Seymour. Hort. Index. 150. 

 Tubeuf. Pflanzenkrankhelten. 329. 

 16 



