34 BULLETIN" *730, XT. S. DEPARTMENT OF AGRICULTURE. 



THE BEST TIME OF APPLICATION. 



Trees were treated at intervals throughout the season to deter- 

 mine the effect of carbon-disulphid solution when applied at the 

 varying stages of seasonal development. With the possible exception 

 of early spring, when the trees are producing their initial foliage, 

 no noticeable injury was observed. Treatment at this time appeared 

 to delay the process of leafing out. With this treatment it is a 

 question of securing ideal conditions of soil moisture, and not essen- 

 tially a question of season. 



Large-Scale Treatments, Using the Liquid Method. 



As a result of the foregoing work experiments involving large num- 

 bers of trees were undertaken. , These large-scale operations required 

 the employment of a 200-gallon power-spraying outfit and the special 

 galvanized-iron tanks shown in Plate VII. The method of preparing 

 and disposing the solution was as follows : 



Having half rilled the spray tank with water, the required amount 

 of carbon disulphid, at the rate of one-half fluid ounce to 4 gallons 

 of water, was poured into the tank and the agitation started and 

 continued' while the remainder of the water was being run into the 

 tank. The agitation was continued while the outfit was being driven 

 from the source of water supply to the location of the trees to be 

 treated, and by this time the water in the tank was evenly charged 

 with carbon disulphid in solution and in suspension as a mechanical 

 mixture. 



The tree basins for the reception of the liquid having been pre- 

 viously prepared, the material was run out through the tanks placed 

 on the top of the engine hood (PL VII, A) to the basins about the 

 trees. In order to secure accuracy in measuring the liquid, the 

 heights in these tanks representing 4 and 8 gallons were indicated 

 by black circles painted on the inside. 



These two auxiliary galvanized-iron tanks (PI. VII, B), having a 

 capacity of 12 gallons each, were connected by a 2-inch Y-pipe to 

 the discharge hose, each of the two arms of the Y-pipe being furnished 

 with a globe valve. The liquid was pumped through a 1-inch hose 

 directly from the 200-gallon tank, and could be directed into either 

 of these two auxiliary tanks at the will of the operator. While one 

 tank was being filled the liquid in the other was being run into a 

 tree basin simply by opening the globe valve belonging to that tank. 

 When empty, the valve was closed and the tank again filled, and 

 during this process the contents of the other tank in turn were 

 emptied into a prepared basin. The process was so regulated that 

 no interruptions were necessary, and 200 gallons of liquid could be 

 disposed of in from 15 to 20 minutes. 



