1900.] PUBLIC DOCUMENT — No. 33. 57 



formation has already been obtained, and it is lioped that 

 another season's experience will atFord considerable insight 

 into the difficulties which now bid fair to prevent the raising 

 of this popular and valuable flower. 



Some Prevalent Diseases of the Year. 

 The following are some rather uncommon diseases which 

 have been unusually prevalent during the past season : — 



The Bacterial Gucutnher Wilt. 



In our last report we gave an account of a wilting of 

 cucumber leaves, due to purely physiological causes. A 

 disease of the same plant, and having a very similar effect, 

 but caused by bacteria, is well known, and appeared in this 

 vicinity in out-of-door cucumbers this year. In this case 

 the bacteria which cause the trouble develop mostly in the 

 ducts of the stem and leaf petioles, multiplying rapidly, and 

 causing a stoppage of the flow of sap and hence a wilting of 

 the leaves. The organisms can be readily seen, oozing out 

 in little drops from the cut ends of affected parts. Pure 

 cultures may be easily obtained from these drops. 



No remedy can be given as yet for this disease, other than 

 the removal and burning of affected plants. 



A Geranium Disease. 

 In our annual report for 1897 we described a leaf-spot 

 disease of the cultivated geranium (Pelargonium), which 

 was thought to be caused by bacteria. It appeared at that 

 time in a very wet season, and seemed more a result of 

 the abnormal conditions than a true disease. The same 

 trouble has been abundant during the past season, however, 

 and appears to be a dangerous enemy to the growth of this 

 plant. It causes small yellow and dead spots in the leaves, 

 so that they fall off, and the plant becomes nearly denuded 

 in the worst cases. Examination showed, as before, that 

 the dead spots are full of bacteria, and no other organisms 

 could be found, the former appearing to be the cause of the 

 disease. Attempts were made to isolate the organisms, but 



