Diseases of Plants 291 
The root-knot disease, which is caused by small “ eel- 
worms,” may be confused with the clubroot disease, in the 
southern states especially. The worms infest the roots 
and produce swellings, but these are smaller than the 
swellings of the clubroot. By breaking open the swollen 
roots, one may often detect pearly white bodies about 
the size of a pin head; these are the female eelworms. 
To combat this animal parasite, practice crop rotation, 
destroy all diseased plants, and clean the frames and flats, 
as is recommended for the clubroot. 
BACTERIAL WILT OF VINE CROPS 
This disease is caused by a bacterium that lives 
within the woody vessels which carry sap up to the leaves. 
This parasite is so minute that many thousands of them 
can live together within a single cell of the host plant. 
In time, the vessels are broken down and cavities formed 
within the host. The supply of water is thus checked, 
and the plant suddenly wilts and soon dies. There is no 
recovery and no cure for plants after the germs once get 
inside. 
The minute germs of this disease are carried from 
diseased plants to healthy cnes by the striped cucumber 
beetle. This insect chews into diseased plants and gets 
the bacteria on its mouth parts; then when it chews into 
healthy plants, the bacteria gain an entrance. 
The best measures of prevention are: (1) to destroy 
and combat the striped beetle, and (2) to burn all plants 
as soon as they become infected. 
The various vine crops also wilt suddenly and die when 
attacked by the grub of the stalk borer, but in this case 
