64 



BACTERIAL DISEASES OF PLANTS 



Sandwich Islands. — There is a serious banana disease but its 

 cause is not known (1915). It attacks the Chinese banana. 

 There is a serious potato disease and a bad shade tree disease, 

 both of unknown orip;in. The mosaic of sugar-cane occurs. 



Great Britain and Germany. — Until recently in these countries 

 not much critical study was given to bacteria as a cause of plant 



Fig. 46. — Costa Rican peudo-canker of citrus. A detail from Fig. 45, further 

 enlarged to show absence of any translucent border such as that shown in Fig. 

 48. Photographed by transmitted light. X 6. 



diseases, but now good students are at work. Potato rots are 

 probably the most destructive bacterial diseases. Appel has 

 described one and Spieckermann another. The bacterial 

 potato rot Pethybridge and Murphy described from Ireland^ is 

 like the German "black leg." Wormald has described a rot 

 of celery which is common also in the United States (Fig. 49). 



1 Proc. R. Irish Acad., vol. xxix, Sect. B, No. 1, 1911. 



