470 DISEASES OF ECONOMIC PLANTS 



OLEANDER 



Bacillose, knot, gall (Bacillus). — This disease both upon 

 leaves and stems appears to be identical with that upon 

 the olive.^ Smith of CaUfornia believes it to be caused by 

 the same germ as that upon the olive, while E. F. Smith 

 thinks it is different. 



ORCHIDS 



Botryose (Botrytis vulgaris Fr.). — The plants are often 

 rendered unsightly and the flowers valueless by straw-col- 

 ored spots. They are at first very minute, but enlarge 

 rapidly and involve large areas. A gray mold similar to 

 that found upon the lily appears later. 



All infected refuse should be burned. 



PALM 



Colletotrichose {Colletotrichum sp.). — Palms often die 

 and turn black at the tips of the leaf segments, or similar 

 spots may appear upon other parts of the leaf. These 

 spots near their edges have a watery appearance. When 

 they become dry, purplish acervuli appear. Upon seed- 

 lings the disease is particularly troublesome, resulting in 

 failure of the leaves to unfold. 



The blighted parts should be cut away and burned and the 

 remaining foliage sprayed at least once each week with 

 Bordeaux mixture or ammoniacal copper carbonate. 



PANSY 



Colletotrichose (Colletotrichum violce-tricolori^ R. E. 

 Smith). — This blight has been noted in many states. It is 



1 Smith, C. O., Bot. Gaz. 42, 301, October, 1906. 



