12 COMMON WEEDS 



WEED "HOST." FUNGUS. 



( White Root-rot (Rosellinia neca- 

 Many Species . . .. . 



( Sclerotium Disease (Sclerotinia 

 >' >' ' ; * "j sclerotiorum Mass.). 



( Blindness in Barley and Oats 



Wild Barley (Hordeum murinum} < ( Helininthosporium graminenm 



( Erikss.). 



Shepherd's Purse and other Cru- ) White Rust of Cabbages (Cysto- 

 cifers . . . . .) pus candidus Lev.). 



f Violet Root-rot (Rhizoctonia vio- 

 Many Species . . * . < faceaTul.). 



Agrostis canina L., and other ) Reed-mace Fungus (Epichloe ty- 

 grasses . . . ) ^wlHtfTuL). 



( Rust of wheat (Puccinia grami- 

 Barberry \ nis Pers . }< 



( Gooseberry-leaf Cluster-cups (Puc- 

 Sedges (Larex] . . . >\ dnia pr'ingsheimiana Kleb.). 



( Peronosbora effusa Rab., on spin- 

 Goosefoot | acb 



, ( Rosellinia radiciperda Mass. A 

 Docks, Sorrel, and many others | Whhe Root . rot ^ n New Zealand. 



, / TJ . . N (Chrysanthemum Rust (Puccinia 



Hawkweed (Hieradum} . . j h ] eracii Mart)< 



Groundsel, Ragwort, and other ) Pine Cluster-cups (Peridermium 

 species of Senedo . . . ) pini Wallr.). 



., j ^ f Ergot of rye (Claviceps purpurca 



Many wild Grasses . . . \ J^.^ x 



These few data will make it quite clear that weeds 

 may frequently be of great importance in connection 

 with insect and fungous infestations. 



(e) Weeds may be Parasitic on certain Crops. Some 

 weeds are actually parasites living on the crop under 

 cultivation, feeding on the juices elaborated by the crop 



