Lespedeza 
Bacterial wilt, southern blight, and root-knot nematodes damage 
the lespedeza crop in most areas where it is grown. The root-kmot 
nematode has become so destructive in the sandy soils of the 
Coastal Plain that susceptible varieties can no longer be grown 
successfully in that region. Fortunately nematode-resistant strains 
heve been developed, and one is now being grown. Use of resistant 
varieties in the future may be expected to reduce loss from nema- 
todes by 5 or 6 million dollars. Southern blight kills the plants 
soon after they are attacked, and the loss varies considerably 
from year to year. Crop rotations that limit the regular establish- 
ment of lespedeza are helpful in controlling blight. The develop- 
ment of disease-resistant varieties appears to be the best remedy 
for bacterial wilt. 
Soybeans 
About half of the 25 diseases ettacking soybeans in the United 
States are of economic importance. The annual reduction in soybean 
yields caused by diseases has averaged 12.5 percent during the last 
10 years, amounting to 73 million dollars. The bacterial diseases, 
blight, pustule, and wildfire, are most widespread. They cause 
severe defoliation and substantial reductions in yield. Prior to 
1948 the bacterial diseases were important only in the South, but 
now they are destructive to soybeans in the Midwest as well. Varie- 
ties resistant to pustule and wildfire will soon be in production 
in the South, but no resistant varieties are available for the Midwest. 
The two most important fungus diseases, stem canker and brown stem 
rot, infect the stems and may cause the plants to die before seeds 
are matured, or greatly reduce the quantity of seed produced when 
the plants are not killed. They occur in the heavy producing areas 
of the Midwest, where it is not uncommon to find fields in which 
half the plants have been killed. Such infection greatly reduces 
yields and demonstrates how destructive these two diseases may be- 
come. More than a thousand selections have been tested for resis- 
tance to these diseases, but no resistant ones have been found. 
Other important fungus diseases include downy mildew, which occurs 
each year in all soybean-producing areas of the United States; brown 
spot, which has been particularly severe in IMdiana and Ohio; frogeye, 
which may be found in all producing areas some years and has been 
particularly severe in Indiana; rhizoctonia root rot, which occurs 
primarily in the northern portion of the soybean-producing area and 
has caused heavy damage in the heavy producing State of Minnesota. 
Targetspot, which has been found only in the Southern States, was 
observed first in 195 and has been destructive in Louisiana and 
Mississippi in some years since that date. 
Virus diseases have caused little damage to soybeans in general, 
but have oceasionally caused serious losses in localized areas along 
the Mississippi River in Iowa, DT1linois, and Missouri. 
