Oct. 21, i9i8 Angular-Leaf Spot of Cucumber 217 



«i REMEDIAL MEASURES 



The matter of finding some means of controlling angular-leafspot has 

 been kept in mind in all the studies, especially in comparing cucumber 

 varieties as to susceptibility, in observing the ways in which the disease 

 is spread, in testing the sensitiveness of the organism to desiccation, to 

 heat and chemical germicides, and in trying to determine how the bac- 

 teria are overwintered. 



RESISTANT VARIETIES 



Tests made in the field in 191 5 and 191 6 by growing the horticultural 

 varieties (listed on page 206) where they were exposed to infection yielded 

 no encouraging results. There was no marked difference in susceptibility 

 between the varieties. No instance of individual resistance has been 

 observed in all the fields which have been examined. 



SANITATION 



The evidence recorded under the section on dissemination by pickers 

 justifies the recommendation that where feasible the picking of fields into 

 which the disease has been introduced be done at times other than in 

 early mornings or on rainy days when the bacterial exudate is abundant. 

 In cases where it is necessary to pick over a partly diseased field under 

 those unfavorable conditions it may be worth while to pick the healthy 

 part of the field first. 



The hope for the complete control of the insect pests, particularly the 

 cucumber beetles, seems to be a thing for which there is little basis. The 

 fact, however, as discussed under the consideration of dissemination, 

 that there is good evidence that these insects are instrumental in spread- 

 ing the disease from one field to another makes more urgent the need of 

 finding better ways of holding them in check. 



SPRAYING 



Spraying experiments in which Bordeaux mixture (3-6-50) was the 

 principal fungicide used, were under observation in Wisconsin during the 

 summers of 191 4, 1915, and 1916. Noticeable checking of the disease 

 resulted each year. Yield results were in all cases so vitiated by factors 

 other than the spraying, especially the mosaic disease, that comparisons 

 of them were of little value. Furthermore, the disease did not develop 

 in the most destructive way on the experimental fields. The data at 

 hand therefore hardly justify a definite statement of the value of spray- 

 ing for this disease, but, in the opinion of the writer, the practice would 

 not in Wisconsin and neighboring States be generally profitable on a com- 

 mercial scale. Several reasons have fumishd the basis for this conclu- 

 sion. Because of the early appearance of the disease, spraying, to be 

 most effective, would have to be started nearly as soon as the plants 

 came up. Because of this need for beginning early and continuing the 



