78 
THE GEAPE 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 by relative 
occurrence of larvae 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 larva?. 
Un- 
sprayed 
plat. 
Sprayed 
plat. 
April and May 
September 25, 1907 
Mav 27-28, 1908.... 
June 19, 1909 
September 25, 1909 
20-vear Concord 
....do 
....do 
....do 
....do 
76 
92 
100 
67 
115 
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. 
