120 



Let us now consider the part that each of the above 

 points play in producing high class fruit free from diseases, 



THOROUGHNESS OF APPLICATION. 



First, what constitutes a thorough application? To 

 state it briefly, thoroughness means putting enough material 

 to do the work in all places where work is to be done. To 

 insure complete control, a tree infested by San Jose scale 

 must be sprayed in such a way that every scale is covered 

 with the insecticide. This means that the spray must be 

 driven into the crevices of the bark, forced behind and un- 

 der bud scales, and through the fine, hairy covering of the 

 young shoots. In spraying peach trees for leaf curl every 

 bud, twig and branch must be coated with a thin layer of 

 spray material. Any part of the tree that is not covered 

 remains exposed to infestation by the leaf curl fungus. In 

 spraying for the codling moth every apple whose calyx cup 

 does not receive its share of poison is liable to be injured or 

 destroyed by the young worm eating its way into the seed 

 cavity. On the other hand we must bear in mind that it is 

 possible to apply too much material, which not only results 

 in unnecessary waste, l)ut, with active growing trees may 

 cause severe injury to both fruit and foliage. If the nozzle 

 is held too long in one position, thereby drenching certain 

 branches the danger of injury is materially increased. The 

 solution collects in drops on the leaves ; these drops coalesce 

 to form large ones and as the solution evaporates it becomes 

 more concentrated and burns. We find that a relatively 

 coarse spray applied at very high pressure is more likely to 

 cause burning than a fine spray applied with moderate press- 

 ure. It is a noticeable fact that foliage injury, as a result 

 of spraying, has been more common since power sprayers 

 rame into general use than it was when applications were 

 commonly made with pumps producing low pressure. It is 

 claimed by some that a coarse spray applied under very high 

 pressure is necessary to control codling moth, but in our ex- 

 perience a fine spray with moderate pressure gives just a» 



