CONTROL OF GRAPE-BERRY MOTH. 11 
The experiments were extended in 1918 to include work in 15 vine- 
yards, but as infestation was not sufficiently heavy for satisfactory 
comparisons in all the vineyards only the 5 showing the heaviest 
infestations are included in Tables III and IV. 
The arsenicals were applied in Bordeaux 2-2-50 in vineyards Nos. 
1, 2, and 5. In vineyards Nos. 3 and 4 copper sulphate was omitted 
at the request of the owners. Stone lime 2 pounds to 50 gallons was 
retained to care for any free arsenic in the arsenicals. Resin fish-oil 
soap at the rate of 1 pound to 50 gallons was used uniformly through- 
out the experiments. 
METHOD OF RECORDING RESULTS OF SPRAYING EXPERIMENTS. 
It had been learned in earlier work * that results based on weights of 
harvested fruit were misleading, owing to the varying thrift of vine- 
yards, time of harvest, weather conditions affecting the development 
of worms, etc. The weight method, therefore, was abandoned in 
favor of the count method. This consists in selecting a representa- 
tive number of vines in each sprayed plat and in each check, har- 
vesting all the fruit from these vines, counting the clusters, then 
the clusters containing wormy berries, then removing the wormy 
grapes and counting them. To ascertain the average number of 
grapes per cluster, 100 representative clusters were taken in each 
vineyard and all the grapes counted. The number of clusters in 
each plat was then multiplied by the average number of grapes per 
cluster to give the total number of grapes examined in each plat. 
In all control work on the grape-berry moth, the unevenness of in- 
festation within a vineyard has made experimental results difficult to 
interpret. This uneven infestation prevailed throughout these in- 
vestigations but was cared for whenever possible by placing checks 
across the control plats and reading the results on the control plat 
the second post-length away from the checks. While the plan does 
not entirely overcome the difficulty, the writers feel that the averages 
from several vineyards closely approximate actual conditions. 
In all cases the fruit from at least 10 vines was examined and when 
possible the examinations included all the fruit from 20 to 25 vines. 
Exceptions to this occurred only when there were less than 10 vines 
of a particular variety in a plat. First-brood counts were made in 
some instances, but since they add little to the final results they are 
omitted from the tables. 
1 Johnson, Fred, and Hammar, A. G., op. cit. ; Isely, Dwight, op. cit. 
