VEGETABLE AND FIELD CROPS 217 



destructive through a large territory, particularly in the 

 Southern States, and at least as far north as Ohio. 



The chief symptom is yellowing and falling of lower 

 leaves, and eventually all of the leaves except those of the 

 head. This character may be strongly emphasized 

 upon one side or even upon one side of single leaves. 

 Affected plants are retarded in growth and often die. After 

 death abundant pink acervuli are seen. 



In treatment the same methods should be followed that 

 are suggested for cabbage black rot; especially should af- 

 fected land be avoided, and the young plants grown in 

 healthy soil. 



CANTALOUPE AND MUSKMELON 



Leaf blight {Alternaria Brassicce (Berk.) Sacc. var. 

 nigrescens Pegl) . — The leaf blight and downy mildew are 

 the most destructive diseases of the cantaloupe and musk- 

 melon in this country. In Florida, in some seasons, nearly 

 the whole commercial crop is lost. Much damage has been 

 reported from Ohio, Indiana, and Colorado. 



The leaf blight begins as small round brown spots usually 

 marked by concentric rings. In the centers of these spots 

 the hjqjhae develop a moldlike growth. The spots en- 

 large to a centimeter or more, coalesce, dry, and cause the 

 leaf to curl and shrivel at the margin. The petioles and 

 veins are also affected. The ripening of the melons is 

 hastened, but the quality is destroyed, the fruit becoming 

 soft, wilted, insipid, and valueless. 



If melons be repeatedly grown upon the same field, the 

 disease increases year by year; hence rotation should be 

 practiced, and resistant varieties should be used. A 



