Vegetable and Field Crops 181 



yellowing, turn brown, die, and become ragged in appear- 

 ance. Tendrils, buds, and petioles turn black and die. Upon 

 the stems and fruit the spots are sunken and bear numerous 

 acervuli. Its most conspicuous form is upon the fruit at any 

 age, especially at maturity. Here very characteristic sunken 

 spots with pink centers, much like the bean pod-spot, are 

 produced. Upon old melons they do but slight injury, but to 

 young fruit the attack is often fatal. A bitter taste is often 

 imparted to the fruit. The disease is spread through the 

 field by rain and surface drainage water, and winters in the 

 field. It is probably carried to new fields by the seed. 



Spraying with 4-4-50 Bordeaux mixture is recommended. 

 Clean seed should be used, or the seed disinfected. It is also 

 well to destroy infective refuse and to practice rotation. 



Wilt '-^^ {Fusarium vasinfectum Atk.) — The melon wilt 

 not only destroys the growing crop, but prevents the suc- 

 cessful culture of melons upon the field in question in suc- 

 ceeding years. It is less frequently met on the muskmelon 

 than on watermelons. A similar wilt of squash is said to 

 be caused by a different Fusarium. The wilt has spread, 

 rapidly during the past decade, and is now known from the 

 Atlantic to the Pacific, and from the Gulf to Iowa. 



The first symptom appears in the leaves which droop as 

 though they were suffering from want of moisture. The 

 leaves and runners wilt rapidly, and this is soon followed by 

 the death of the entire plant. 



Upon cutting the main tap root across near the surface 

 of the ground, the wood presents a yellow color, making a 

 distinct contrast with the white wood of the healthy plants. 

 This one character, taken together with the wilted appear- 

 ance of the vine, enables recognition of the true wilt. The 

 further fact that a field once infested shows the same disease 

 in succeeding years in the same or in extended areas is an 

 additional recognition mark. 



Its spread may occur in the ways mentioned under soil 

 diseases and in particular through the use of infested manure. 



To restrict it to its present confines, crop rotation should 



