No. 6. DEPARTMENT OF AGRICULTURE. 247 



ing, and there is nothing that is readih' injured except the scales. 

 A thorough application then made will kill off the very forms that 

 would otherwise live safely through the winter. A thorough appli- 

 cation in late June and another in early October should keep the 

 trees fairly safe without winter treatment. Ordinarily, however, 

 the fruit grower prefers to make his radical applications in winter, 

 and in that case his summer applications are intended mainly to 

 prevent the tree from being severely injured before winter sets in. 

 The soap mixture may be applied at any time when needed, and at 

 least once every two weeks after the middle of June the owner of an 

 infested orchard should go through it carefully enough to determine 

 whether any trees need treatment. 



Instead of soap, kerosene or crude petroleum may be used. These 

 are much more effective but require much more care in their use. 



A fruit grower at Middlebush, X. J., uses summer applications of 

 crude oil in his plum orchard continuously and finds no difficulty in 

 controlling the scale. He keeps his trees trimmed low and under 

 constant supervision. When he notices considerable «cale breeding 

 on any tree, he applies the oil by means of a knap-sack sprayer 

 through a fine Vermorel nozzle. The application is made to the 

 trunk and larger branches only, and in general, in the centre of the 

 tree; foliage being avoided so far as possible. As the oil kills the in- 

 sects in all stages, the sprayed portion becomes and remains clean for 

 the balance of the season. In this way, though the trees are always 

 more or less infested, the insects are kept down to harmless num- 

 bers. It requires some experience before a man uses crude oil con- 

 fidently; but when that experience has been gained, it is surprising 

 how freely it may be used with safety. I have treated the trunks and 

 branches of peach trees with equal success and equal safety; but I 

 would advise caution and experimental applications on such trees 

 before adopting the method on a large scale. The rule should be, 

 just as fine a spray as possible and just enough to wet the treated 

 surface. The trees should be dry when the application is made. 



Kerosene of the grade used for illuminating may be used instead of 

 the crude oil and is safer. It kills the insects almost as well, and is 

 not so hard on the foliage; but it has no protective effect and, within 

 twenty-four hours after an application has been made, scale larvae 

 may set safely on the treated surface. Those who have learnt how 

 to use kerosene prefer it to the crude oil, and it is certainly cleaner. 

 The same rule as to the character of the spray and the dryness of the 

 tree should be observed as with crude oil. In addition, the day itself 

 should be dry, that the rapid evaporation of the oil may be favored. 

 The insects are killed as soon as the oil penetrates them; the earlier 

 it disappears thereafter, the better for the tree. 



