SPRAYING AGAINST THE GRAPE LEAFHOPPER. 11 



this spraying, and Mr. Pierce is confident that under favorable condi- 

 tions the cost per acre could be materially reduced. 



A portion of the vineyard on the farm of Mr. John Higgins which 

 has been seriously infested by the grape leafhopper, to which he 

 attributes the shrinkage of several thousand baskets of fruit during 

 the past two or three seasons, was treated in the same manner as the 

 vineyard of Mr. H. H. Harper. 



On three blocks, however, the strength was varied as follows: 

 Blackleaf tobacco extract, 1 gallon to 75, to 100, and to 150 gallons of 

 water. As far as could be observed the dilution to 150 gallons of 

 water was as effective as that to 75 gallons. All of the applications 

 mentioned above were made before any of the nymphs had completed 

 the final molt, and all of them were highly effective in reducing the 

 number of the nymphs to a point where their injury for the remainder 

 of the season was very slight. On all of these treated blocks the 

 foliage remained dark green and growth continued until quite late in 

 the season, whereas in adjacent infested and unsprayed vineyards the 

 foliage commenced to turn brown before the fruit was ready to pick. 

 In fact, the sprayed and the unsprayed portions of these vineyards 

 were readily distinguished within two or three weeks after the appli- 

 cation was made, and the difference in the condition of the foliage 

 became more marked as the season advanced. 



Plate II shows photographs of vines taken in the experimental 

 vineyard of Mr. H. H. Harper. Figure 1 is an unsprayed vine, and 

 shows the exposure of the fruit by loss of a part of the foliage and 

 also the withered condition of the leaves still attached to the vines, 

 as a result of grape leafhopper injury. Figure 2 shows the perfect 

 condition of the foliage on a vine growing in the adjacent row which 

 was sprayed with tobacco extract. There is just as much fruit on 

 the vine shown in figure 2 as on the vine shown in figure 1, but 

 owing to the perfect condition of the foliage it can not be seen. The 

 injurious effect of this pest upon the crop yield is cumulative. As a 

 result of several seasons of infestation the cane growth of the vine 

 is stunted during the growing season, and the final outcome is a 

 sickly vine producing small clusters of poorly ripened fruit. 



The owners of all of these vineyards were satisfied with the results 

 of these experiments, and are planning .to treat their entire vine- 

 yards with the tobacco extract next season if the insect is present in 

 them in injurious numbers. 



As the season advanced toward August 1, vineyardists began to 

 observe the serious nature of the injury wrought by this pest. Most 

 of them were unprepared to treat it, however, since they had no 

 spraying material on hand, and many of the nymphs were passing 

 from the last molt and developing wings. Nevertheless it was pos- 

 sible to undertake another experiment on the vineyard of Mr. Charles 



