TWENTY-FIRST ANNUAL MEETING. 191 



As a barrel of spray mixture will cover from five to eighteen 

 apple trees, it makes the cost of material alone for three 

 sprayings with good fungicide, like Bordeaux or commer- 

 cial lime-sulphur, two of which include arsenate of lead as 

 an insecticide, from 6 to 24 cents per tree, according to the 

 size of the tree. Half of this cost is for the fungicide and 

 half for the insecticide. 



Spray Injury. There are three types of injury, especial- 

 ly on apples, that may result from spraying, namely, leaf- 

 burn, scorch and russeting of the fruit. Leaf-burn usually 

 shows in the form of specks or small round spots of a red- 

 dish-brown color that appear suddenly or gradually in the 

 tissues. Often these spots run together into irregular and 

 larger areas. Sometimes the injury is so severe as to 

 amount to a scorch, and the whole, or the greater part, of 

 the tissues are killed. 



AA'^ith Bordeaux mixture this injury is rather gradual 

 in its development, and some of the leaves which turn yel- 

 low and drop ofif show little burn. We have seen trees 

 where one-third to two-thirds of the leaves w^ere shed. Ap- 

 parently more injury occurs when the leaves are fully 

 grown than when they are immature, as the rapidly expand- 

 ing tissues stretch out the spray coating with their growth. 

 Hence, we believe the first spraying, at 4-4-50, and the oth- 

 ers, at 1-4-50, are not likely to cause serious injury except 

 under unusual conditions. Bordeaux injury to the foliage 

 was much more prominent in 1910 than in 1911. This was 

 partly due to the difference in the season, and partly to the 

 use of weaker Bordeaux in the latter year. 



The commercial lime-sulphur sprays have given, on the 

 whole, considerable less leaf injury on apples than Bor- 

 deaux, this being limited usually to a slight burn on scat- 

 tered leaves or on one side of the tree. Thomsen's lime 

 and sulphur, however, in 1911. gave more than the normal 

 amount of leaf-burn. 



