CONTROL OF GRAPE-BERRY MOTH. 19 



The lime was slaked to a smooth paste with 18 ounces of water. 

 The arsenic acid was diluted with the remaining 16 ounces of water 

 and the diluted acid added to the lime paste a little at a time. The 

 paste was stirred vigorously during the mixing. With each addi- 

 tion of acid the lime had a tendency to granulate, but continued 

 stirring restored the smooth pasty condition. A sample of the final 

 paste was analyzed by the United States Bureau of Chemistry under 

 miscellaneous laboratory No. 24714 as follows : 



Moisture 69.7 



Total CaO (as received) 15.08 



Total As 2 B (as received) 12.04 



Water soluble As 2 5 .02 



5 grams samples in 1,000 c. c. C0 2 free water ; equivalent to 2 pounds to 

 50 gallons. Free lime calculated as calcium hydroxid Ca(OH)a 4.4 per cent. 



Paste made according to this formula was used on grapes in 1918 

 at the rate of 4 pounds to 50 gallons of water. Grape-berry moth 

 infestation failed to develop in numbers sufficient for the desired 

 comparisons in any one of the four vineyards in which these ma- 

 terials were used. The spreading qualities and effects on grape 

 foliage, however, are important. The arsenicals were applied either 

 in Bordeaux 2-2-50 or with stone lime 2 pounds to 50 gallons added 

 to the mixture. In all cases resin fish-oil soap at the rate of 1 

 pound to 50 gallons was also added. The paste made from sodium 

 arsenate spread equally as well as the commercial arsenate of cal- 

 cium powder or arsenate of lead powder. The paste made from ar- 

 senic acid failed to spread as well and when dry it was not a smooth, 

 even coating such as is desired. In no case could foliage injury be 

 attributed directly to the use of either of the home-made arsenate of 

 calcium pastes. 



Spbeaders and Adhesives. 



Because of the partial failure of arsenate of lead and Bordeaux 

 to spread over or " wet " the individual grapes in the grape clusters, 

 various materials have been added to these to facilitate the spreading 

 process. 



The qualities desired in such a spreader are (1) quick-wetting 

 power, (2) adhesive power when dry, and (3) that it be easily pre- 

 pared for use. In addition, a material to be suitable must be com- 

 patible with Bordeaux mixture and arsenicals and also be compara- 

 tively cheap. 



Former investigations 1 had shown that some form of soap was 

 the most practical material for the purpose. When these investiga- 

 tions were undertaken various soaps were recommended by differ- 



1 Isely, Dwight, op. cit. 



