238 Diseases of Truck Crops 



die from a wilt in the same field where squashes are 

 not thriving. However, the writer has been able to 

 prove that the wilt of cowpea and okra are diseases 

 caused by two distinct species of Fusarium, and that 

 both of these parasites may be found in the same field 

 also infected with Fusarium cucurbitce of the squash. 



Root Rot, see Rhizoctonia, p. 45. 



Root Knot, see Nematode, p. 49. 



DISEASES OF THE WATERMELON (Citrullus 



vulgaris) 



Malnutrition 



Cause, physiological. 



Malnutrition seems to occur in fields deficient in 

 potash. The trouble is apparently new, brought 

 about by the scarcity of potash, due to war conditions. 

 The disease is characterized by light brown spots 

 located around the veins and margins of the leaf. 

 The disease must be further investigated before re- 

 medial measures may be suggested. 



Bacterial Wilt, see Cantaloupe, p. 219. 



Downy Mildew, see Cucumber, p. 230. 



Powdery Mildew t , see Cucumber, p. 222. 



Honey Dew or Sooty Mold 



Caused by Capnodium sp. 



Watermelon stems, petioles, and leaves often be- 

 come coated with a black sooty growth. This is 



