4io 
Journal of Agricultural Research 
VoLXXV, No 10 
Tabi^E III .—Spray control of leaf and twig infection, Knightsiown, IQ 20 
Tree. 
Sprays applied 2,4, and 6 weeks 
after petal-fall. 
Petiole infection. 
Twig infection, 1920 wood. 
Number 
examined. 
Percentage 
infected. 
Number 
examined. 
Percentage 
infected. 
Cankers per 
100 twigs. 
2R2 .... 
None (L. S. 1 to 3, dor.)« 
757 
3 6 
102 
63 
115 
3R2 .... 
None (L. S. 1 to3, dor.).. 
697 
39 
112 
62 
137 
2R5 .... 
None. 
I, IOI 
1,063 
15 
103 
15 
18. 4 
2R6.... 
None. 
24 
I42 
22 
30-3 
3^3 • • 
Bordeaux 4-6-50. 
954 
0. 6 
114 
1.8 
1.8 
2R4.... 
.do. 
1,057 
0. 1 
120 
0.8 
0.8 
6R4. . 
1,049 
1,360 
0. 4 
no 
0 
0 
2R7 .... 
.do. 
0. 2 
100 
0 
0 
8R7 .... 
1, 124 
0. 2 
117 
0 
0 
3 r8.... 
Lime sulphur 1 to 40... 
T > °37 
0 
129 
0.8 
X 
9 r8 .... 
1, 220 
0 
no 
0.9 
1 
a X,ime sulphur, 1 to 3, dormant. 
The results in Table III show that the blotch sprays applied 2, 4, 
and 6 weeks after petal-fall gave a very perfect control of petiole and 
twig infection, and that twig infection is strictly correlated with petiole 
infection. The importance of the latter consequently becomes apparent. 
The control of fruit infection, to be presented in another publication, 
was in all cases comparable to the control of petiole infection. Lime 
sulphur appeared to be as effective as Bordeaux, but the following year 
it proved less so. The dormant spray of lime sulphur 1 to 3 exerted 
no control whatever. 
The effectiveness of the blotch sprays against twig infection is further 
attested by the fact that cankers were very abundant on the 1919 wood 
of the same trees in which practically none appeared on wood formed 
in 1920, the year the blotch sprays were first applied. 
At Mooresville, in 1921, information was obtained relative to the 
ineffectiveness of dusts in controlling petiole infection. These results 
are presented in Table IV. These results indicate that dusting failed 
to prevent leaf infection. 
TabeE IV .—Dusts versus spray , Mooresville, 1921 
Petiole infection. 
Applications 2, 4, and 6 weeks after petal-fall. 
Number 
examined. 
Percentage 
infected. 
Sulphur dust. 
283 
184 
2, 067 
611 
35 
So 
4 
Bordeaux dust.. 
Bordeaux spray. 
None. 
94 
The effectiveness of Bordeaux (3-5-50) blotch sprays against petiole 
infection was noted by C. L. Burkholder on Ben Davis at Solon in south¬ 
ern Indiana. Out of 893 leaves from unsprayed trees, 88 per cent showed 
petiole infection, and none of the 2,182 leaves from sprayed trees showed 
any infection. 
