248 ANNUAL REPORT OF THE Off. Doc. 



Vigorous, raiikly growing trees are mucli less susceptible to in- 

 jury from oil applications than are those in which the growth is 

 feeble and the bark hide-bound. The horticulturist who prefers to 

 rely upon summer applications must remember that scale insects 

 never sleep, have no Sundays or holidays and when once started 

 breed continuously. 



Persistent applications of whitewash are often very useful. Lime 

 alone is not of much use against the scales, but if, just before the 

 breeding begins, a thorough coating of lime wash be sprayed on the 

 trunks and branches the young will find it impossible to set on the 

 sprayed areas. Many indeed will be killed and many of the breed- 

 ing females will be destroyed. If a coating be applied before the 

 middle of May, the males when they hatch cannot gain access to 

 the covered females and many will remain unimpregnated. Thus 

 with lime alone a very decent sort of campaign may be made. The 

 first application should be made about May lUth, the second, one 

 month later, June 10th. Thereafter applications may be made as 

 often as the covering becomes badly worn. A little salt adds greatly 

 to the sticking qualities of the material. The wash should be spray- 

 ed on as is the Bordeaux or other mixture in which lime is used and 

 it should alw'ays be strained before using. 



