REMEDIAL MEASURES. • 71 



So serious was the injury of the larvae to the roots at this date that 

 the large crop of fruit which some of these vines were carrying was 

 actually shriveling up and dropping to the ground. By the fol- 

 lowing spring many of these vines had either died outright or were 

 in a very weakened condition. Plate IV, figure 2, gives an example 

 of the manner in which the fibers had been removed from the roots 

 of many of these young vines by the larvae of the root- worm, and 

 shows the limited growth of new canes as a result of the infestation 

 which rendered the vine incapable of producing a crop of fruit during 

 the coming season. Thus the variety of conditions existing in this 

 vineyard was such as to enable us to work out several features of 

 the problem on the same block, namely, the effect of a poison-spray 

 application on vines of different varieties, of diflferent ages, and in 

 different stages of injury, all growing side by side under practically 

 the same conditions. All of the vineyard was subjected to the 

 same treatment in regard to cultivating, fertilizing, and spraying, 

 with the exception of six rows running through the center of the 

 block (PI. VI) which cut through all four of the sections mentioned 

 above. These six rows were reserved as a check and from these 

 the spraying alone was withheld. 



Below are given all of the data relating to the experiment conducted 

 on this vineyard during the seasons of 1907, 1908, and 1909, together 

 with the results obtained. 



As the time for the emergence of the beetles from the soil drew 

 near daily visits were made to this vineyard during the latter end 

 of June and early July, 1907. On July 15 an occasional beetle was 

 found feeding on foliage near the ground. All preparations had 

 been made for spraying as soon as the first beetles appeared, and 

 the first application was made at this date. The sprayer used was 

 a gasoline-engine power outfit constructed especially for vineyard 

 work (PI. X, fig. 2). The regular Bordeaux formula, 5-5-50, was 

 used, and to this 3 pounds of arsenate of lead were added, this latter 

 ingredient being the active poison agent of the spray. A pressure 

 of about 100 pounds was maintained throughout the application, 

 and about 100 gallons of spray mixture were applied per acre. Fixed 

 nozzles were used of the eddy chamber type. 



On July 23 a second application was made, the same formula 

 being used and the same pressure maintained. 



During the season of 1908-9 the same spray formula, machinery, 

 and nozzle arrangement were used and the same pressure main- 

 tained. The only varying factor was the dates of application, which 

 varied each season with the date of emergence of the beetles. To 

 facilitate comparison, the dates of application, effect of spray on 

 egg deposition, prevalence of larvae at roots, and crop yield as com- 

 pared with the unsprayed check are tabulated for the three seasons. 

 (Tables XXVI, XXVII, and XXVIII.) 



