32 BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 



Usually when "trailer" applications were made the sprayer was 

 driven only in every other alley between the grape rows, each rod- 

 man spraying both sides of his row on the same trip. 



During the season of 1915, in the Moorhead vineyard, Plats II and 

 IV, the sprayer was driven in every alley, each rodman spraying only 

 one side of a row on each trip. While it was easier to cover the foliage 

 by this method, it was slower and it showed no distinct advantage 

 over the usual method, in controlling the berry moth. It was given 

 no further trial. Which of the two methods is best is probably a 

 matter of individual preference. 



Careful work was an absolute necessity for successful "trailer" 

 applications. While the responsibility rested chiefly with the rod- 

 men, unless the driver was careful about gathering up the hose and at 

 the same time allowing the rodmen time to finish spraying each 

 vine the work was handicapped greatly. It was necessary also that 

 the rodmen should make an effort to cover each cluster or the advan- 

 tage of "trailers" over the strictly mechanical method was lost. 



Time and Number of Applications. 



The most satisfactory spray schedule was as follows: The first 

 application to be made immediately after the falling of the bloom; 

 and the second application abput two weeks later, at the time when 

 the berries are just touching. This proved effective both in 1915 

 and in 1916, and was the schedule used in the majority of plats. 



A single application at the time the berries were just touching 

 reduced the infestation greatly, but hardly offered satisfactory 

 results. It was tried only in the season of 1916. This spray is 

 intended for late first-brood larvse, and enough of the poison will 

 remain on the berries, at the time of the hatching of eggs of the 

 second brood, greatly to reduce this brood as well. The effect of 

 this spray against the second brood is shown by referring to the 

 counts in Bartlett (lower) vineyard, Plat I, in comparison with the 

 adjacent Check Plat A. Plat I was naturally more heavily infested 

 than was Check Plat A, as the first-brood count showed that it had 

 about 50 per cent more infested berries than did "A." On the other 

 hand the final count showed the percentage of infestation in Check 

 Plat A to be three times as heavy as that in Plat I. Similar final 

 results are shown in Southwick vineyard, Plat IV. The results in the 

 Moorhead vineyard, Plat VI, would indicate that in case of light 

 infestation this one application might control the berry moth satis- 

 factorily. 



In 1916 a single application, made on August 12 and aimed directly 

 against the second brood, also reduced the infestation considerably, 

 as shown in Bartlett vineyard Plat II, although the counts did not 

 appear as favorable as the single earlier application previously men- 



