14 BULLETIN 550, U. S. DEPARTMENT OP AGRICULTURE. 



In rainfall during these two months the two seasons showed a differ- 

 ence of 11.34 inches. 



Methods of Application. 



All spray applications were made with a gasoline-power sprayer. 

 Two methods of applying the spray were used. (See PI. V.) By 

 the one, spray was applied to the vines by a "set-nozzle" arrange- 

 ment at the rear end of the machine. From vertical pipes on each 

 side of the machine two short spurs were directed outward, each 

 bearing an angle nozzle which drove the spray outward and upward 

 and as far as possible under the leaves. The lower spur was below the 

 lowest wire of the trellis. The height of this spur could be varied 

 somewhat to suit the trellis. A third and upper nozzle was mounted 

 on a longer spur and projected over the trellis, the nozzle being di- 

 rected downward. The "set-nozzle" method of application of spray 

 is more generally used against the grape rootworm and mildew, be- 

 cause it is least expensive from the labor standpoint. 



By the other method single nozzles were mounted on short rods at- 

 tached to the machine by trailing hose, and the spray was directed to 

 the grape clusters by hand. This "trailer" method has been recom- 

 mended by Johnson in his investigations against the grapevine leaf- 

 hopper. 



The two methods require about the same amount of spray material 

 per acre. When "set nozzles" were used about 150 gallons of spray 

 was applied per acre; with "trailers," about 125 gallons per acre was 

 used immediately after the falling of the blossoms, and about 175 

 gallons when the berries began to touch. 



When applications were made with "set nozzles" the machine 

 was driven along every row, but when "trailers" were used the 

 machine was usually driven only along alternate rows, the rodman 

 on each side being able to reach through the trellis and spray both 

 sides of the row. 



The spraying schedules followed in these investigations were based 

 largely on the seasonal-history studies on the grape-berry moth 

 made by Johnson and Hammar, modifications being made the second 

 and third seasons. 



Spraying Experiments in 1914. 



From a control standpoint the spraying in 1914 was a failure, 

 although it did bring about a consistent reduction in the numbers 

 of the berry moths. Furthermore, results in the Phillips vineyard 

 were of uncertain value because of the wide variation of infestation 

 as shown by the checks. The negative results were of value, how- 

 ever, since they indicated the necessity of a radical revision of 

 spraying practice. 



In applying the spray, the difficulty in covering the grape clusters 

 with "set nozzles" was apparent. It was noted also that even when 



