CONTROL OP THE GRAPE-BEKRY MOTH. 29 



From Table 21 it may be seen that fish-oil and laundry soaps used 

 in the seasons of 1915 and 1916 were both effective as adhesives and 

 that soft soap and flour paste were unsatisfactory. (See PI. VI.) 

 The advantage of one soap over another, as shown in the final counts, 

 was usually so slight that it can not be considered significant. 



At the time of application resin fish-oil soap appeared at best 

 advantage. It was a better spreader than any of the others and 

 consequently made the work faster and easier. It was used only in 

 the Bartlett vineyard during the season of 1916. The potash fish-oil 

 soap without resin also spread better than laundry soap. Potash 

 fish-oil soap was used in 1915 in the Miller and Carlburg vineyard 

 and in 1916 in the Moorhead and Bartlett. vineyards. 



The following analysis of the resin fish-oil soap used was made by 

 the Bureau of Chemistry: 



Water, 25.7 per cent. 4 



Fatty and resin anhydrides, 68 per cent. 

 Sodium oxide, Na 2 0, 4.3 per cent. 

 Undetermined, 2 per cent. 



Laundry soap if carefully used is practically as effective and adhe- 

 sive as the fish-oil soaps, but it has two distinct disadvantages, (1) it 

 is a slower and a poorer spreader than fish-oil soaps, and (2) different 

 makes of soap and even different lots of soap of the same make vary. 

 In the experimental work each brand of soap was tried on a few 

 vines with a hand sprayer before it was used in commercial experi- 

 ments. If the vineyardist finds it necessary to rely on laundry soaps 

 for an adhesive, this precaution would be advisable. 



All of the laundry soaps that proved satisfactory were yellow resin 

 soaps. Some of the so-called white soaps containing no resin were 

 tried with a hand sprayer but lacked adhesive qualities and were not 

 used in any field experiments. 



Cutting the laundry soap and allowing it to dry out before using it in 

 the spray mixture seemed to impair its sticking as well as its spread- 

 ing qualities seriously. 



A soft soap from a rendering factory also was tried, but gave nega- 

 tive results both as an adhesive and as a spreader. This was observed 

 readily at the time of application, and the result is shown clearly in 

 the final counts. (Moorhead vineyard, Plat V, 1916.) 



Flour paste although a good spreader was an unsatisfactory adhe- 

 sive, because it washed off with the first rain. (Miller and Carlburg 

 vineyard, Plat VIII, 1915.) 



When soap in the spray mixture is not dissolved thoroughly, 

 clogging of the spray apparatus is likely to follow. Hot water was 

 found necessary for quickest results. If the sprayer engine is water 

 cooled, hot water from the water jacket can be used satisfactorily 

 for this purpose. 



