ANTHRACNOSE OF CUCURBITS. 



59 



As to resistant varieties, it should be mentioned that among water- 

 melons the citron is somewhat resistant, while practically all varieties 

 of cucumber and muskmelon tested are susceptible. 



SPRAYING. 



As was pointed out in the historical account, many workers have 

 held Bordeaux mixture to be an effective control for this disease, 

 and the same opinion seems to be rather widely held at the present 

 time. 



At Princeton in 1915 plat tests were made of a variety of commer- 

 cial sprays and of various Bordeaux formulas. None of the applica- 

 tions seemed to control anthracnose, since it spread consistently 

 through the sprayed rows. 



In 1916 at Madison block tests were made with Bordeaux mixture 

 (3-6-50 formula plus soap) and row tests with Pyrox and other 

 strengths of Bordeaux mixture. Anthracnose spread through the 

 sprayed rows as well as the controls, and neither observational nor 

 yield-record evidence indicated that any of the spray applications 

 controlled the disease. Its severity was, however, somewhat checked 

 by the sprays, since it was very serious in only 5 out of 17 sprayed 

 rows, as compared with 7 out of 11 unsprayed controls. 



To gain some insight into the effect of the presence of the spray 

 upon leaf infection, a series of atomizer inoculations were made on 

 August 13 upon the upper surfaces of certain leaves and the lower 

 surfaces of other leaves among the sprayed rows. Well-sprayed 

 leaves were chosen. The results of these inoculations are presented 

 in Table X. 



Table X.- 



-Results of atomizer inoculation of sprayed cucumber leaves at Madison, Wis., 

 in 1916. 



Spray treatment. 



None ' 



Do 



Do 



B ordeaux mixture , 3-6-50 formula. 



Do 



Do 



Do 



Bordeaux mixture. 2-4-50 formula 



Do 



Bordeaux mixture, 4-6-50 formula 



Do 



Pyrox 



Do 



Number of 

 leaves. 



Surface 

 inoculated. 



Both... 

 Upper 

 Lower 

 Upper 

 Lower 

 Upper 

 Lower 

 Upper 

 Lower 

 Upper. 

 Lower. 

 Upper 

 Lower. 



Results, Aug. 24. 



— (8 located. No infection). 

 ? 



— (9 located). 



+(9 located; all infected). 



+ (7 typically infected). 

 + (6 typically infected). 

 + (4 typically infected). 

 + (9 typically infected). 



While natural infection interfered to some extent with these tests, 

 no unquestionable atomizer infection occurred in any case where the 

 upper epidermis of sprayed leaves was inoculated, while in all cases 

 some typical atomizer infection was secured where the lower epidermis 

 of sprayed leaves was inoculated. Of these leaves, only the upper epi- 



