CUCUMBER SCAB CAUSED BY CLADOSPOKTUM 

 CUCUMERINUM.i 



BY S. P. DOOLrrrLK. 

 IMPORTANCE OF THE DISELVSE. 



The scab or "black spot" of cucumbers caused by ClaclospoHum 

 cuoumerlnum Ell. & Artli., was first noted in the United States about 

 1887 and since that time has been reported as generally prevalent 

 in both this country and Europe. It has appeared at various times 

 in nearly all parts of the United States where large quantities of 

 cucumbers are grown and is also quite common in England and 

 Germany. 



The disease is found both in the field and in the greenhouse but 

 is more especially connected with the growing of cucumbers for 

 pickling, since the young fruits used for this purpose are most 

 susceptible. 



During the past two seasons it has been very severe in the states 

 of Michigan, Indiana, and Wisconsin. This territory is the center 

 of the i)ickle growing industry and the crop reaches a high valua- 

 tion each year. 



The fact that the nature of the fungus causes it to spread from 

 field to field with great rapidity and that the young fruits are the 

 most subject to attack makes the loss severe. 



This is not all due to the actual fungus injury however, but to 

 the fact that the scab lesions give a point of entrance to various 

 soft rots. When the cucumbers are mixed together after picking, 

 the rotted ones affect the sound fruits as well and they become use- 

 less for pickling. 



The difficulty and expense of sorting out all damaged fruit, a 

 thing which the average grower will not do thoroughly, has led' 

 many salting stations to refuse all the fruit from fields which are 

 seriously infested with the fungus. This greatly increases the loss 

 to the grower since he has no other means of disposal of the crop. 



The disease was particularly severe last season at Big Ka})ids, 

 ^licliigan, and in the northern part of the State in general. In 

 this locality the yield was greatly reduced although there are no 



1. Part of Ihosis presented for degree M. S. at the Michigan Agricultural Col- 

 lege. IDl"), under the II. .1. Heinz Industrial FeUowsliip. 



