studied the question for years, says in the 1920 Fruit 

 Growers' Association of N. S. report p. 82, "A mix- 

 ture of kaolin and nicotine sulphate dried and pul- 

 verized has been used with success in California 

 against the Walnut aphis. We have combined both 

 free nicotine and nicotine sulphate with sulphur and 

 arsenate of lead, thus securing a "3-in-l" mixture, 

 and used with a good effect upon smaller sucking 

 insects such as psyllids. On larger more resistant 

 species, e.g. plant bugs (iliridae), though an apparent 

 reduction was obtained, the results were not entirely 

 satisfactory for the strength tested." 



Professor Caesar in the 47th annual report of the 

 Entomological Society of Ontario says: "Finely ground 

 soluble-sulphur mixed with hydrated lime gave me 

 fairly good results on San Jose Scale,"" though he also 

 says that the mixture was a troublesome one to apply. 

 It is evident that progress has been made, and the 

 thought which is now being expended on this problem 



f 



by numerous invesligators, is sufficient to anticipate 

 a successful solution. To date, however, dust must be 

 considered decidedly inferior to spray in the control 

 of sucking insects. 



Comparative Costs. 



Not many records seem to have been kept of com- 

 ]iarative costs, for so many factors have to be taken into 

 consideration. The capital required for machinery to 

 treat a given acreage, depreciation, gasoline, mat- 

 erial, labor, are all factors, some of them difficult to 

 make comparative. The writers have kept strict re- 

 cords over large areas and a detailed discussion of 

 these appears in the 1919 Proceedings of the N. S. En- 

 tomological Society, p. 90, 91, 92. During the two 

 seasons of 1919 and 1920 the cost of treating an acre of 

 orchard in Nova Seotia throughout the season has 

 l)eeu as follows : 



Spray (N.S. Spray Calendar) $20 to $25 



90-10 sulphur and lead arsenate dust .... .$23 to $32 

 Copjier-arsenic dust $15 to $20 



11 Nova Scotia du.stiug lias, for the most part, been 

 cliea])er tliaii sin-aying. The difference in any locality 

 will probably not be great. 



Dusters at work in the carl.v morning. Note tlie slow drift of 

 dn.st when the air is calm and damp. 



Upper end of E.xperiniental Orchard. 



