POTATO DISEASES IN HAWAII. 39 
Control. — In Maine it is thought that the disease does not spread 
from hill to hill, and that it can be controlled there by seed selection 
and disinfection. Here, where there is little change of season, it is 
conceivable that the disease might remain in the field from crop to 
crop, and be much more serious. The porous, well-drained soils 
would tend to minimize the damage should this disease be introduced. 
The liability of introducing this disease as well as others is added 
evidence against the practice of using any imported seed except that 
which is certified. The latter should be planted only after it has been 
examined and disinfected, as a small percentage of this disease is 
allowed in the growing fields, the product of which may later be 
certified. 
Southern Bacterial Wilt (Bacillus solanaeeariim) . 
This bacterial disease of the Irish potato is prevalent and destruc- 
tive in the Atlantic States from Florida to New Jersey. Tomatoes, 
eggplant, peppers, and tobacco are also attacked. On tobacco the 
disease is known as the Granville wilt. This malady is most destruc- 
tive in dry seasons and on dry soils. The affected plants wilt, 
recover during the night, and wilt again the next day. Then they 
become yellowed or blackened, and the forming tubers are attacked 
by a soft rot, which is accompanied by a very foul odor. Possibly 
this disease would be very destructive if introduced into the islands, 
but considering the remoteness of the infected districts, there seems 
little probability of this contingency. 
Control. — Seed from uninfected fields should be selected and rota- 
tion of crops practiced. Other solanaceous crops should be avoided 
in the rotation. Insects should be controlled, as they are believed to 
carry the wilt from plant to plant. 
Silver Scubf (Spondylocladdum atrovirens). 
This disease, probably recently introduced into the United States, 
is caused by the fungus Spondyloclculiwn atrovirens and is charac- 
terized by a silvery appearance of the skin, with minute blackish 
patches of the fungus thereon. It is not considered as especially 
serious. The damage to the crop results from disfigurement, abnor- 
mal shrinkage and shriveling of the tubers, and decreased market 
value of the product. 
Control. — Seed selection and disinfection in corrosive sublimate 
are advised for the control of silver scurf. 
Verticillium Wilt {VerticiUium alhoatmm). 
Another wilt disease scarcely to be distinguished from the Fu- 
sarium wilt is caused by the fungus VerticiUium olboatrum. Besides 
the potato, this fungus attacks eggplant, tomato, okra, and cotton. 
