SAVING OF FOLIAGE. 79 



Genoral consideration of the above tal)lo develops some strikino- 

 eontrasts. By addint^ the ligures eorrespondinjr to the average per- 

 centage of diseased leaves on the trees of the control rows, and dividing 

 this amount by the num))er of rows, we find that in the entire l)lock, 

 containing 200 contiol trees, 83.(3 per cent of the leaves were ])adly 

 diseased at the date of this estimate. In contrast to this, the total of 

 the average percentages of disease shown by the trees of the sprayed 

 rows, divided by the num])er of sprayed rows in the l)lock, shows the 

 average amount of disease in the sprayed rows to have been 26.2 per 

 cent. Evidently this average is nuich above the percentage of disease 

 shown at that date ])y many separate rows, as it included the rows 

 treated with noneffective sprays as well as those giving the ])est 

 results. Adding the averages of rows 4, 24, and 53 and dividing the 

 amount })y 3 gives 82 per cent of disease as the average of the 

 three rows. As noted in the table, these rows were not sprayed in 

 1895, but were left in order to ascertain the effects of the sprays 

 applied to them in 1894, and the average of disease is seen to bo prac- 

 tically as great as upon rows never sprayed. 



From the date of this first estimate the progress of the disease in 

 the orchard was verv marked. Within the next two weeks the fungrus 

 fruited (^uite generally upon the swollen leaves, and a large percentage 

 of the worst diseased leaves had fallen from the trees. By May 9 

 the contrast between sprayed and unsprayed trees had quite generally 

 reached its highest point, and any irregularities of special trees, etc., 

 could no longer be considered. On May 9 a second careful estimate of 

 the foliage was made. In this work, however, it was impossible to 

 estimate the amount of disease on the trees as compared with the total 

 amount of foliage present, as had first been done, for much of the 

 diseased foliage had already fallen. To avoid this difficulty a new 

 method of estimating was adopted. From the entire ))lock of trees 

 were selected two rows, Nos. 21 and 22, which showed only from 4 to 

 6 per cent of disease, and were in other respects in perfect foliage. A 

 careful studv of these rows was made to gfet a clear idea of the con- 

 dition of a tree in full foliage at that date, and with these types in 

 mind each tree of the entire block was carefully examined. An esti- 

 mate was made for each tree, based on the twenty typical trees studied, 

 to determine the per cent of perfect foliage upon it, taking the amount 

 which should be upon the tree at that date, if no disease existed, as 

 100 per cent. The following table gives the results of this work. The 

 percentages in the last column represent the gain in leaves of spra^^ed 

 trees over the average of all control trees in the block. The manner 

 of obtaining these percentages is discussed on page 85. 



