408 Diseases of Economic Plants 



Slime-mold {Physanmi, cinereimi (Bat.) Pers.). — This 

 mold grows as a slimy mass over any plants that are in its 

 path, often covering an area a meter square. It later changes 

 to the gray, dusty, sporing stage. It is not really parasitic or 

 even injurious, but by its unsightliness, arouses the apprehen- 

 sion of the gardener. No treatment is needed. 



Root-Tot {Thielavia). See p. 23. Among the ornamentals, 

 this disease has been noted particularly on Aralia, Begonia, 

 Cyclamen, Dahlia, sweet pea, violet, Tropoeolum. 



Sooty-mold (Capnodium) may occur on almost any plant, 

 though usually with little or no injury. It is most harmful 

 on the camelha. (See p. 413). Other plants on which it is 

 often seen are privet, Lonicera, palms, Cornus, yew, oleander, 

 rhododendron. 



Crown-gall (Pseudomonas). See p. 87. Crown-gall is not 

 usually troublesome on ornamentals. It has been noted on 

 daisy. Evonymus, honeysuckle, rose, flowering almond, 

 chrysanthemum. 



Southern-blight (Sclerotiwn rolfsii). See p. 23. The fun- 

 gus that causes this disease may be found on almost any 

 host, especially in the South. Even as far north as Illinois 

 it was destructive in gardens on Campanula, Erigeron, 

 Dianthus, Dracocephalum, Pentstemon, Phlox, Eupatorium. 



Special Diseases 



AGAVE 



Anthracnose (Colletotrichum agaves Cav.). — Spots are 

 produced on the leaves, and often cause the death of young 

 plants. Diseased leaves should be removed and burned, and 

 the remaining leaves sprayed. 



AMARANTUS (Various cultivated varieties). 



White-rust (Albugo) is common but not serious. See 

 p. 164. 



