Family Cucurbitaceae 229 



tract the disease. The trouble is spread by insects, 

 the principal of which is the melon louse, Aphis 

 gossypii Glov., as well as the striped cucumber beetle, 

 Diabrotica vittala. Satisfactory control methods are 

 still wanting. Diseased plants should be destroyed 

 and the field sprayed for insect pests. 



Bacterial Wilt 



Caused by Bacillus tracheiphillus Ew. Sm. 



The symptoms and damage caused by this wilt 

 have already been discussed under the cantaloupe, 

 p. 219. Recent investigations by Rand and Enlows 1 

 have shown that seeds from diseased plantsfail to 

 reproduce wilt. This is true not only for the cucum- 

 ber, but also for all the other cucurbit hosts which are 

 subject to this trouble. Of the numerous varieties 

 of cucumber and cantaloupe tested, none shows 

 promise of resistance. While the Marblehead, Gol- 

 den Bronze, and Boston Marrow are very susceptible 

 varieties of the squash, the Mammoth White Bush 

 and the Early White Bush seem to be immune to wilt. 



Angular Leaf Spot 



Caused by Pseudomonas lachrymans Sm. and Bry. 



This disease seems to be common on cucumbers in 

 Florida, Michigan, and in Wisconsin. It has been 



1 Rand, F. V., and Enlows, E. M. A., U. S. Dept. of Agr., Jour. 

 Agr. Research, 6 : 417-434, 1916. 



