54 



BEAN CULTURE 



not carried to healthy beans from diseased plants 

 by insects or some other means. The fungus con- 

 sists entirely of tiny colorless threads in the tissue 

 of the bean and the spores produced at the surface 

 of the black spots. After a heavy rain or dew these 

 spores may easily become attached to insects which 

 visit the diseased plants and so be carried to healthy 

 ones. 



Hoeing the beans when they are wet is also sure 

 to scatter the spores in flying drops of water. While 



FIG. 17 BEAN LEAF BEETLE. (a), ADULT BEETLE; 



(b), pupa; (c), larva; (/), eggs. 



the weather is not directly responsible for the dis- 

 ease itself, it has very much to do with the preva- 

 lence and destructiveness of anthracnose. When 

 there is an abundance of moisture, the spore masses 

 quickly dissolve and the spores are easily distrib- 

 uted by insects, rabbits, or other animals running 



