Root and stalk rots cause weakened plants, small poorly filled 
heads, and broken-over plants. Yields of forage and grain, as well 
as feeding value, are reduced. 
Sorgo, called also sweet or swar sorghum, is subject to the 
diseases that affect other sorghums, especially the leaf spots and 
anthracnose. It is also affected bv red rot, esnecially in stalks 
stored for processing, 
Sugar Beets 
Sugar beet losses come from fungus, bacterial, and.virus diseases. 
In beet-growing districts east of the Rocky Mountains leaf spot and 
black root, both fungus diseases, cause the heaviest losses, Leaf 
spot reduces both tonnage and quality by its destruction of the 
leaves. Black root, which is most serious in the districts where 
beets are grown under conditions of natural rainfall, causes poor 
stands, Both diseases resuit either in abandonment of acreage or 
in very low yields from such acres as are retained, Many of the 
plants that escape death as seedlings make only a stunted growth, 
In years with above=-normal rainfall the crop, instead of benefiting 
by the moisture, suffers from leaf disease and poor stands. 
Curly top, a virus disease transmitted by the beet leafhopper, is 
prevalent in the sugar-beet districts west of the Rocky Mountains. 
Although largely controlled by resistant varieties, this disease 
still lowers yields in many western States. 
Minor diseases, including mildew, rust, and crown rot, also take a 
definite toll. The sugar-beet nematode and other nematodes limit 
production, particularly in the West and Midwest districts. 
In all districts sugar beets in storage piles at factories are sub=- 
ject to losses from decay organisms that rot the roots, Factories 
are able to prevent much of this loss by installing air ducts through 
which cool night air is blown through the storage piles; but deteriora- 
tion of the beets from storage rots in spite of ventilation is still 
a serious drain on the crop. 
Sugar Cane 
Sugar cane yields are still reduced by mosaic, but this destructive. 
disease of the twenties is now largely controlled by use of resistant 
varieties. Recently ratoon stunting, caused by a virus, was recog- 
nized in the United States as associated with deterioration of sugar= 
cane plantings in the second and third years of growth. The losses 
from this disease greatly augment the losses from Pythium root rot 
and red rot, two fungus diseases that bring about poor stands and cause 
deterioration of the stalks. These rots are serious in both Louisiana 
and Florida. Losses of sugar cane grown for sugar reduce the crop 
13.5 percent; losses of sugar cane grown for sirup are lower because 
of less damage from red rot. On the other hand, mosaic does more 
