CONTROL OF THE GRAPE-BERRY MOTH. 9 



BAGGING GRAPE CLUSTERS. 



The bagging of grapes immediately after the setting of fruit, to 

 prevent infestation by the berry moth, was tried in the season of 1914 

 in the vineyard of the late Mr. J. L. Spofford. Clusters on 25 vines 

 were covered with paper bags, 2 and 3 pound sizes. The bags were 

 fastened on the clusters with long pins and a slit was cut in the 

 bottom of each bag to drain out whatever water might collect. 



The experiment was successful in so far as exclusion of the moth 

 was concerned. Only 20 wormy berries were found in 100 clusters 

 which averaged 32 berries to the cluster. This was a total infestation 

 of only 0.62 per cent. However, the test was not severe, for the 

 infestation of the grapes on the surrounding vines was light, being 

 only 13.2 per cent. The infestation of the bagged clusters was due 

 no doubt to oviposition which had taken place before the bags had 

 been placed on the clusters. 



The cost of bagging, however, is prohibitive in commercial vine- 

 yards in the Erie-Chautauqua grape region. Brooks (10) records, 

 in control measures against the grape curculio, that one laborer in 

 his employ could bag 1,200 clusters a day. This was probably 

 exceptionally fast work. Using this as a basis and figuring 550 

 vines per acre, each bearing 40 clusters, or a total of 22,000 clusters, 

 the minimum cost of bagging an acre of grapes, according to 1914 

 prices, would be as follows: 



Applying bags $22. 91 



Cost of bags, $1.15 per 1,000 25. 30 



Pins, $0.10 per 1,000 2. 20 



Total 50. 41 



This method of control, if followed at all, would be practicable only 

 in a garden vineyard. 



HAND PICKING INFESTED BERRIES. 



Attempts to control the grape-berry moth by hand picking the 

 fruit infested by first-generation larvae, in order to prevent subsequent 

 infestation, were made in the seasons of 1914 and 1915. Clear-cut 

 comparisons between the hand-picked plats and the checks were 

 impossible because of the flight of moths from one row to another. 



Experiment in Adams and Gill Vineyard op North East, Pa., 1914. 



The plat chosen for the hand-picking experiment was a narrow strip 

 of eight rows, containing slightly more than 1 acre, located in a 

 corner of the vineyard, and bordered by a hedgerow. This plat was 

 from three to four times as grossly infested as was the greater part of 

 the vineyard. After the six rows nearest the hedge, the percentage of 

 infestation declined quite rapidly as compared with that of the rest 

 of the vineyard, and the south end, which was lower than the rest of the 

 plat, was even more heavily infested than the rows next to the hedge. 



87069°— Bull. 550—17 2 



