112 STATE BOARD OF AGRICULTURE 



si'UAViNG i:xi'i:uiMi:xTS. 



For several seasons there has been considerable injury to apple 

 orchards in various i)arts of the State from canker-worms and tent- 

 caterpillars, both of which feed on the foliage durin^^ the early sprin*^. 

 The station orchards have been regularly sprayed for the last ten 

 years and neither of the insects named have been found for some time, 

 so that it has not been possible to illustrate the method of combatting 

 them. Some years ago, however, both of them were to be found upon 

 the trees and we were convinced that the remedy which was elfective 

 at that time and which, used as a preventive, has since kept them from 

 regaining a foothold in the orchard, would be found equally effective 

 in other orchards, although man}' to whom we recommended it reported 

 that it was of no value. The treatment consisted of the thorough 

 spraying of the trees with Paris green, or white arsenic. To prevent 

 the burning of the foliage and their being washed off by the spring 

 showers, it was recommended that either freshly slaked stone lime, 

 or Bordeaux mixture, be added to the spraying comjjound. The use 

 of the latter is desirable, as it will also aid in controlling the attack 

 of fungous diseases. AVhile a few reported partial or entire failure 

 from the use of this spraying mixture, others found it to be an un- 

 qualified success. 



To serve as an object lesson and to demonstrate that the insects men- 

 tioned above could be readih' controlled, arrangements were made with 

 C. E. Hadsell, of Troy, Mich., who had recently come into the possession 

 of a seventeen acre apple orchard, some twenty-five years old, whicli 

 had been badly infested with the tent-caterpillar, and in which the 

 canker-worm had been at work for five years. In 11)00, the worms 

 had become so numerous that the trees in the center of the orchard 

 looked as if burned with fire, while those at the east and west ends 

 were considerably injured. Sjjraying was commenced in 1001, just 

 before the opening of the blossoms and a second application was made 

 soon after the blossoms dropped, ^yhile the trees were in bloom, 

 and at the time of the second application, the larva^ were hatching 

 and were numbered by the thousand upon single trees, but a careful 

 examination on June 17 showed the orchard to be free from worms, 

 and there was no indication in the api)earance of the foliage that any 

 harm had been done. At the same time all of the foliage upon un- 

 sprayed trees was found to be destroyed. 



The arsenic was yjrex^ared by boiling one pound in two gallons of 

 water with two pounds of lime for forty minutes, and then adding it 

 to 250 gallons of Bordeaux mixture. There is of course nothing new in 

 the fact that these insects can be controlled by spraying with arsenites, 

 it having been demonstrated fully twenty years ago, and the failures 

 that have been reported must be attributed to lack of thoroughness in 

 spraying, or to putting it off so long that the larvae were nearly full 

 grown, when a large amount of poison would be required to kill them, 

 and to obtain it they would have to eat enough of the leaves to nearly, 

 if not quite, defoliate the trees. When two applications are made, at 

 the times recommended above, and the work is done so thoroughly that 



