some bacterial diseases of plants. 127 



The Wilt of Cucumbers, Melons, and Squashes. 



As compared with the Fire Bhght the WiU of Cucumbers is of 

 comparative recent appearance. At least it has not been suffi- 

 ciently destructive to attract attention until within the last few 

 years. It seems to be increasing very rapidly at least in New York 

 and the New England States. It is even now one of the most 

 destructive of cucumber diseases and bids fair to rival in severity 

 the well-known Mildew of cucumbers and melons. 



The first indication of the disease in a cucumber patch is the 

 wilting of a leaf here and there on the vines during the heated part 

 of the day. The leaf at first recovers during the night. After a 

 clay or two it fails to revive. If examined the leaf will show when 

 held to the light dark water-soaked areas along the main veins, 

 usually near the base of the blade. The diseased leaf now dries up 

 at the top of the erect leaf stalk. The wilting of the leaf is soon 

 followed by the wilting of all that portion of the vine from the 

 diseased leaf to the tip and finally of the entire vine. If you cut 

 across one of the diseased leaf stalks or wilted vines a watery 

 liquid will ooze out. This is viscid and will draw out into long 

 threads if the cut surface be touched with the finger and then slowly 

 drawn away. This is a sure field test of the bacterial nature of 

 the disease as the oozing liquid is made up of multitudes of the 

 bacteria held together by their mucilaginous coats. 



The disease frequently appears in greenhouses where cucumbers 

 are grown out of season, especially where they are grown in late 

 fall and early winter. I have seen entire houses just coming into 

 bearing entirely wiped out by thig disease. 



The bacteria work chiefly in the sap tubes of the vine, clogging 

 or choking them and finally destroying them altogether. They get 

 into the leaf tissues, as I shall explain presently, and work their 

 Avay through the leaf veins down the stem to the vine by way of the 

 sap tubes. This cuts off the sap supply to the parts above causing 

 them to wilt and die. Very often the disease finds its way into the 

 fruit, either by way of the stem or through the blossoms. It works 

 chiefly in the vascular region just under the skin, giving the flesh 

 a mottled watery appearance. If the fruit is cut open the viscid 

 liquid will ooze out. It sometimes comes out on the surface through 



