20 



BULLETIN 837, U. S. DEPARTMENT OF AGRICULTURE. 



ent authorities. To determine the most efficient of these, experiments 

 as shown in Table VIII were conducted in 1916. 



Table VIII. — Relative efficiency of different soaps as spreaders and adhesives, 

 Schonhardt vineyard, Venice, Ohio, 1916. 





Pounds 



in 50 

 gallons. 



Spray 

 mate- 

 rials 

 com- 

 bined 

 with 

 soaps. 



Gallons 

 spray 

 mate- 

 rial 

 per 

 plat 

 second 

 appli- 

 cation. 



In- 

 crease 

 over 

 resin 

 soap. 



Results in grape-berry moth control. 



Kind of soap used. 



Num- 

 ber 

 vines 

 exam- 

 ined. 



Num- 

 ber 

 clus- 

 ters 

 exam- 

 ined. 



Num- 

 ber 

 grapes 

 exam- 

 ined. 



In- 

 fested 

 grapes. 



Variety. 



Soft 



2 

 1 



( l ) 

 (') 

 0) 



140 

 100 

 75 



Per ct. 



86 



33 

 



/ 14 

 I 10 



/ H 



l io 



/ 12 



\ io 



/ 22 

 \ 31 



790 

 342 

 608 

 198 

 735 

 311 

 1,050 

 1,019 



18,960 

 12,996 

 14,592 

 7,524 

 17,640 

 11,918 

 25,200 

 30,570 



Per ct. 

 17.04 

 24.83 

 6.78 

 6.11 

 8.50 

 8.37 

 41.16 

 73.12 



Concords. 





Catawbas. 

 Concords. 





Catawbas. 

 Concords. 



Checks 



Catawbas. 

 Concords. 

 Catawbas. 













1 Bordeaux 3-3-50, arsenate of lead commercial powder 2J pounds to 50 gallons. 



Adjoining grape rows, each row including Concord and Catawba 

 varieties, were sprayed three times during the season, the first ap- 

 plication three to five days after grape bloom, June 27, the second 

 when the grapes touched in the clusters, July 13, and the third at 

 the beginning of the hatching period of second-brood larvae, August 

 3. All spraying was done by the trailer method with medium disk 

 angle nozzles and at a pressure of 150 pounds. The soaps were used 

 as spreaders in mixtures of Bordeaux 3-3-50 and arsenate of lead 

 powder 2^ pounds to 50 gallons. The season was unusually dry dur- 

 ing July and August, favoring both adherence of spray materials 

 and the development of the grape-berry moth. The Concords were 

 harvested September 29 and the Catawbas October 10. 



The soft soap used was a bulk product made especially for use in 

 commercial laundries. This soap dissolved readily in hot water, but 

 when applied to grapes formed in globules on the leaves and grape 

 berries and dried in large drops. This condition was reflected in 

 the percentages of infested grapes at harvest time, 17 per cent on 

 Concords and 25 per cent on Catawbas. This increase in infestation 

 on the Catawba variety did not occur with the laundry or resin soap, 

 and so seems to indicate less adhesive power late in the season in the 

 soft soap, since the Catawbas were harvested 12 days later than the 

 Concords. The laundry soap used (PL IV, fig. 1) was the com- 

 mon yellow-bar soap, chipped and dissolved in hot water. This 

 spread smoothly over the grape foliage and berries and gave a satis- 

 factory covering when the spray was directed on the clusters for a 

 sufficiently long time, but the amount required to " wet " them was 

 33 per cent greater than when the resin soap was used. When the 

 third-spray application is used, as in this experiment, the adhesive 



