New York Agricultural Experiment Station. 349 



cucumbers, melons, etc., is of the opinion that the bacterium 

 which causes this disease of cucurbitaceous plants is identical 

 with the one which causes a wilt disease of potatoes and toma- 

 toes, common in the Southern States and not infrequently found 

 as far north as the latitude of New York City. But recent investi- 

 gations made by Dr. Erwin F. Smith* show that the wilt dis- 

 ease of potatoes and tomatoes has no connection whatever with 

 the cucumber wilt. He attempted to transmit the disease from 

 the cucumber to the tomato and potato by artificial inoculation 

 but failed in every case. Moreover, he comes to the conclusiouf 

 that there are two distinct wilt diseases of the cucumber. Which 

 one of these caused the wilting of Long Island cucumbers the 

 past season we do not know. Along what is known as the Port 

 Jefferson Branch of the Long Island Railroad the loss from the 

 cucumber wilt was considerable, although not so great as the 

 loss from downy mildew to be mentioned later. 



In the present state of our knowledge of the wilt disease no 

 remedy for it can be recommended. Rotation of crops has been 

 suggested as a remedy and probably it does tend to lessen the 

 virulence of the disease, but it cannot be relied upon. The past 

 season we found a bad case of cucumber wilt in a field that had 

 been in grass for twelve years. It seems probable that the dis- 

 ease can be communicated by means of cucumber seed. 



It is well known that the white grubs (larvse) of the striped 

 cucumber-beetle feed upon the roots of cucumber plants, and 

 when present in large numbers they may cause the plants to wilt. 

 When present they are readily detected. It is safe to say that 

 almost none of the wilt of late cucumbers on Long Island in 1896 

 was due to this cause. 



We now come to the consideration of the chief cause of the 

 "poor pickle crop" of 1896; namely, the downy mildew. The 

 symptoms of this disease are as follows : The leaves show yellow 

 spots which have no definite outline. If the weather is warm 

 and favorable for the disease these spots enlarge rapidly and run 



* Smith, Erwin P.— A Bacterial Disease of the Tomato, Eggplant and Irish Potato. 

 Bull. No. 12 U. S. Dept. of Agriculture, Division of Vegetable Physiology and Pathol- 

 ogy. Issued Dee. 19, 1896. 



t Loc. cit. p. 6. 



