122 INTERNATIONAL CONGRESS OP VITICULTURE 



leaves estimated both for the dusted and control rows. On the 66 vines of 

 the latter there were 34 vines on which there was mildew on 80 per cent 

 or more of the stems or berries. Four vines only had clusters 60 per cent 

 of which were free and no vine of the controls bore clusters 70 per cent of 

 which were free from mildew. Of the 65 vines dusted, 60 showed 70 per cent 

 and above, mildew-free clusters. On 59 vines 80 per cent or over of the 

 clusters were free from disease. The leaves of the control vines were very 

 generally affected so that the entire row had a distinct grayish cast. It was 

 possible to select the treated rows from the controls from a superficial 

 examination, even by the untrained observer. As in the preceding year no 

 injury to any part of the vine by reason of the treatment was to be seen. 



During the same season, 6 rows of Delaware were dusted in a neighbor- 

 ing vineyard. The first application was made August 1st with a knapsack 

 machine. Five rows of the same vineyard were left as control. A second 

 application was made August 13th with the traction duster. An examination 

 of the vines during the period preceding ripening, and at the time of harvest 

 disclosed very little mildew even on the control rows, with possibly a 

 trifle less on the treated. However, the slight infection made impossible 

 the securing of reliable data. No injury to the vines was to be seen as a 

 result of the sulphur applications. 



In a Concord section of the same vineyard 7 rows of 100 vines each were 

 treated with a dust consisting of 45 pounds of sulphur flour and 5 pounds 

 of powdered arsenate of lead per acre. This application was made July 11, 

 1912. The weather on this day was- hot and clear. A control of several 

 rows containing the same number of vines was left. Owing to the slight 

 infection of mildew on the control vines no data were obtainable as to the 

 efficacy of the treatment. To all appearances the dusted and untreated 

 vines were practically alike. Each matured a good crop of fruit. 



Dusting in 1913. 



During the summer of 1913 the Lindley vineyard was again dusted. 

 Each application was made with the traction machine, the first, July 18th, 

 when the weather was clear and warm; 5 days elapsed before a rain; the 

 second July 30th, a hot, humid day followed by light showers at night. 

 Three rows were left as control, while three and a portion of a fourth immedi- 

 ately adjoining were treated. Through this selection one of the rows that 

 was dusted in 1912 became a control in 1913 while one of the check rows 

 of 1912 received treatment in 1913. The other rows of the vineyard were 

 treated as in 1912. On September 6, 1913, a count was made of the clusters 

 of each plat. Of 2101 clusters examined in the three control rows, 20G2 

 showed mildew of some degree while but 29 clusters could be classed as 

 entirely free, i. e., 1.3 per cent of the entire number. 2151 clusters were 

 examined from the 66 dusted vines. 1670 of these or 77 per cent were found 

 to be free of the disease. 481 clusters were affected in some degree. The 

 leaves on the untreated vines were very generally affected while those of 

 dusted ones showed only occasional spots of mildew. The sulphur in no 

 way injured any part of the vines. 



