Dormant sprays have been applied in March or early April, before the buds opened, 
and in October or November. 
At regular intervals observations have been made and data recorded relative to the 
effectiveness of each of the fungicides used and to the prevalence of disease. 
SEVEN-YEAR RESULTS FROM SUMMER SPRAYING 
In two experiments dealing with over 2,600 trees, the relative effectiveness of 
Summer spraying with commercial Bordeaux, Koloform and dry wettable flotation sulfur 
has been tested through periods of seven years for the first two sprays, and five years 
for the last named spray. In one experiment commercial Bordeaux and dry wettable flota— 
tion sulfur have been compared directly with each other, each on 474 trees, and with an 
untreated check group of 711 trees. In the other experiment Koloform alone and in com— 
bination with pruning (236 and 230 trees, respectively) has been compared with pruning 
(282 trees) and with an untreated check group (254 trees). 
In these groups the majority of the trees that became diseased had been attacked 
by one of the Phoma wilts, but occasional trees were infected with Cytosporina and 
Verticillium. 
The results obtained year by year and for the entire period of experimentation are 
shown in table 1. Five years of summer spraying with dry wettable flotation sulfur per- 
mitted the development of a greater number of infections than occurred, proportionally, 
among the check trees in the same period. Seven years of summer spraying with commer-— 
cial Bordeaux also permitted a greater proportional development of disease than occurred 
among the check trees. Spraying with these two materials appears, in other words, to 
have favored development of disease to the extent of 14.2 per cent and 9.1 per cent, 
respectively, as indicated in the last column of the table. 
Seven years of summer spraying with Koloform resulted in the occurrence of fewer 
cases of disease than among the untreated check trees. Similar spraying with the same 
material through seven years, with pruning added in each of the last four years, per- 
mitted development of fewer cases of disease, proportionally, than occurred among 
either the check trees or those only sprayed. The degree of control for spraying alone 
is indicated as 8.5 per cent and for the combination of spraying and pruning as 10.1 per 
cent. It is significant that a group of trees in the same block, given no treatment 
other than pruning and that for only the last four of the seven years, developed fewer 
new cases of disease during those four years than occurred in the check. 
FOUR-YEAR RESULTS FROM SUMMER DUSTING 
In an experiment involving nearly 1,400 trees the relative effectiveness of the 
sulfur dusts as summer applications, alone and in combination with pruning, has been 
under test for four years. Six applications of the dusts have been made each summer 
except 1937, when seven applications were made. Kolodust has been applied to the same 
groups of trees throughout the period. Flotation sulfur dust was applied to other 
groups of trees in 1935 and 1936; but, after this sulfur was not available, "Mike" 
sulfur was applied to these groups. 
The prevalent infection in the plot was a species of Phoma, to which is attrib- 
utable about 70 per cent of the total number of cases of disease. Most of the remainder 
of the infections were due to Cytosporina. 
The results obtained year by year, and the degree of disease control for the 
entire period, are given in table’2.; In the untreated, or check, group 171 trees, about 
72 per cent, have become infected. But in the group in which pruning alone has been 
practiced, only 84 trees, about 39 per cent, have contracted disease. Summer dusting 
with Kolodust has permitted 149 trees, or about 64 per cent, to become infected; but 
the Kolodust treatment combined with pruning has permitted only|93 trees, about 47 per 
cent, to become infected. In the tree groups dusted first with flotation sulfur dust 
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