204 The Sugar-Beet in America 
appearance. The shortened petiole resulting from it 
makes the plant resemble one having curly-top, although 
the two diseases are easy to distinguish. The roots of 
plants having the mosaic disease are likely to be dwarfed 
and are often hairy. 
Damping-off. 
The damping-off of seedlings near the surface of the 
ground when they first come up results in considerable 
loss in some districts. This may be caused by a number 
of organisms, among which are Rhizoctonia, Phoma, and 
Pythium. The conditions which favor damping-off are 
heat, abundant moisture, and a weakened condition of 
the seedlings. The elimination of any of these condi- 
tions greatly reduces the difficulty from this cause. Plants 
on heavy clay soils are more subject to the disease than 
those raised on lighter soils. Improving the tilth of these 
soils also reduces the likelihood of injury from damping- 
off. 
