78 



THE GRAPE ROOT-WORM. 



the operation, using about 100 gallons of spray liquid per acre. With 

 this spraying outfit it is possible to cover from 8 to 10 acres of vine- 

 yard per day. 



METHODS OF OBTAINING AND RECORDING RESULTS. 



As in the preceding field experiment, the results of the spray appli- 

 cation were determined by counting the number of egg clusters 

 deposited on the vines by the grape root-worm beetles at a time when 

 the maximum number of eggs were to be found upon the vines. All 

 of the bark was removed from 25 consecutive vines in the unsprayed 

 plat and also in the adjoining sprayed plat. The results of these 

 examinations are given in Table XXIX for the three seasons 1907, 

 1908, and 1909. Table XXX indicates the effect on the larvae of 

 spraying as shown by the number of larvae found at the roots of the 

 vines by carefully removing the soil from the base of the vine for a 

 distance of 3 or 4 feet from the trunk of the vine and to a depth of a 

 foot or 16 inches, going several inches below the second whorl of roots. 



Table XXX. — Effect of poison spray against the grape root-worm as shown hy relative 

 occurrence of larvse at roots of vines in sprayed and unsprayed plats of Porter vineyard^ 

 at North East, Pa., in 1907, 1908, and 1909. 



Date of examination. 



Number 

 of vines. 



Variety and age of 

 vines. 



Number of larvae. 



Un- 

 sprayed 

 plat. 



Sprayed 

 plat. 





40 

 5 

 10 

 12 

 5 



20-year Concord . . . 

 do 



76 

 92 



100 

 67 



115 





September 25, 1907 





May 27-28, 1908 



do 



21 



7 

 19 



June 19, 1909 



do 



September 25, 1909 



do 





When the crop was ready to harvest, the final effect of the season's 

 treatment was obtained for each plat. Table XXXI indicates the 

 plat number, area, fertilizer applied, number of crates or baskets of 

 grapes, net weight of fruit, value per pound or basket, cash value per 

 acre, cost of spraying and fertilizing, and value of crop less cost of 

 treatment. 



The data in Table XXXI, giving the results of the treatment from 

 1907 to 1909, inclusive, show a great increase in crop yield of this 

 vineyard as a result of thorough spraying and heavy fertilization. 

 This experiment proves conclusively that if energetic measures are 

 taken with vineyards rendered practically unprofitable as a result of 

 grape root-worm injury they may be made to yield very profitable 

 crops. 



