678 



Barberry 

 Sedges (Carex) 

 Goosefoot 



WEED FLORA OF IOWA 



I Rust of wheat (Puccinia graminis Pers.) 



\ Gooseberry-leaf Cluster - cup {Puccinia 

 j" pringsheimiana Kleb.) 



!- Peronospora effusa Rab., on spinach. 



Docks, Sorrel, and many "1 Rosellinia radiciperda Mass. A white 



others 



Hawkweed (Hieracium) 



Root-rot in New Zealand. 



Chrysanthemum Rust (Puccinia hieracii 

 Mart.) 



Groundsel, Ragwort, and 'I Pine Cluster-cups (Peridermium pini 

 other species of Senecio j* Wallr.) 



Many wild grasses 



Ergot of rye (Claviceps purpurea Tul.) 



Pig. 525. Leaf rust of Wild Barley (Puccinia rubigo-vera) also occurs on 



wheat. 

 (Drawing by Charlotte M. King.) 



These fungus diseases are particularly noticeable in a number 

 of plants of the mustard family. The Cystopus candidus common 

 upon cabbages in Europe is very common on a large number of 

 cruciferous plants, like mustard, peppergrass, charlock, etc. At 

 times it is very common upon the radish. A related fungus, downy 

 mildew, of the mustard {Peronospora parasitica) is common and 

 troublesome at times on some cultivated members of the mustard 

 family. It is particularly common upon peppergrass and shep- 



