consistently prevalent. Certain other leaf spot diseases are also 
more injurious in these regions than on the processing crep, which 
is largely growm in less humid regions farther north. Fusarium 
wilt and bacterial wilt are more prevalent on the market crop grown 
in the South. On the other hand, anthracnose does not appear until 
tomatoes ripen and is less prevalent on the large portion of the 
fresh-market crop that is picked when green-mature. Virus disezses 
and nonparasitic disorders. are equally prevalent on fresh-market 
and processing tomatoes. 
The same measures are used to control diseases of fresh-market 
tomatoes and tomatoes grown for processing. 
Watermelons 
Severe losses of watermelons are caused by a few diseases. Fusarium 
wilt is present wherever the crop is grown and causes considerable 
loss, although a number of resistant varieties are available. Anthrac- 
nose is widespread in humid areas east of the Continental Divide. It 
causes a leaf spot that can defoliate the vines and a fruit spot that 
is injurious both in the field and in transit. Downy mildew causes 
serious damage in the Atlantic and Gulf States. Rooteknot nematode 
injury is common, particularly on sandy soils in the Southern States. 
Losses from wilt can be greatly reduced by the use of resistant 
varieties, but many popular ones are not wilt-resistant. Seed treat- 
ment, crop rotation, and application of fungicides help to reduce 
losses from anthracnose, but the disease is not well controlled. 
Spraying or dusting will check downy milder, but is not very effec~ 
tive in humid weather. Rotation helps to avoid serious injury from 
root-knot nematodes. 
Drug and Ornamental Crops 
Estimates of disease losses to drug and ornamental crops (Table 5) 
have been restricted to commercial plantings. They do not include 
losses in home gardens and landscaping with the exception of shade 
trees, 
China Asters 
The China aster is an excellent annual for the garden as weil as 
for commercial cut-flower production. Its use is curtailed by two 
serious diseases, Pusarium wilt and aster yellows, each difficult 
to control. 
Wilt causas seedling blight, stem rot, and wilt of growing plants, 
and flower blight of China astars in transit. The fungus is generally 
distributed in the United States, It is sead-borne and can persist 
in infested soil for years. Resistant varieties are erratic in per= 
formance, Commercial producers of cut flowers treat seed and rotate 
or disinfect soil. 
SCOR 
