Sept. 8 ,1923 
Origin and Control of Apple-Blotch Cankers 
411 
The trees at Knightstown recorded in Table III received the same 
sprays in 1921 and the results are shown in Table V. It should be noted 
that the twig infection was, of course, determined the following year. 
Table V. —Spray control of leaf and twig infection , Knightstown , 1921 
Tree. 
Sprays applied 2, 4, and 
6 weeks after petal-fall. - 
Petiole infection. 
Twig infection, 1931 wood. 
Number 
examined. 
Percentage 
infected. 
Number 
examined. 
Percentage 
infected. 
Cankers 
per 100 
twigs. 
2R2 .... 
None (L. S. i to 3 dor.) 
771 
72.4 
IOI 
93 
400 
3R2 .... 
154 
68.8 
IOI 
82 
546 
2R5.... 
None. 
*>353 
I 5-1 
102 
30 
54 
2R6.... 
None (CuS0 4 , 1 to 200, 
1, 210 
41.3 
100 
38 
137 
dor.). 
3R3 • • • • 
Bordeaux, 4-6-50. 
1,340 
0.07 
IOO 
O 
0 
2R4.... 
.do... .*. 
T, 24Q 
0 
100 
O 
O 
6R4. . .. 
.do. 
T, 
0. 08 
IOO 
O 
Q 
2R7.... 
.do. 
I. 283 
0. 8 
IOO 
O 
0 
8R7.... 
X J O 
T. AlC 
Ton 
A 
O 
3R8. ... 
Lime sulphur 1 to 40.... 
x, 
599 
0.14 
10. 9 
X uu 
106 
2.8 
4* 7 
9R8.... 
1,097 
5*3 
IOO 
5 
5 
The results shown in Table V indicate that the Bordeaux blotch 
sprays controlled petiole and twig infection almost perfectly in 1921, 
while lime sulphur proved distinctly less effective. The dormant sprays 
did not influence the disease in the least. 
The control trees were infected much more seriously than in 1920, but 
when compared with each other, show the same relative degree of infec¬ 
tion as in 1920, a condition to which reference will be made later. 
In 1921 lime sulphur 1 to 40 and two strengths of Bordeaux were 
tested on Oldenburg at Mitchell, with results as presented in Table VI. 
All except the control trees received a lime sulphur spray at petal-fall. 
The results in Table VI show that the weaker Bordeaux as well as the 
standard strength effectively prevented petiole infection, while the lime 
sulphur was distinctly unreliable. 
In 1922 the two weeks spray was applied three days late at Knightstown 
and the control of petiole infection was rather poor, as shown in Table 
VII. 
Table VI. —Spray control of petiole infection, Oldenburg variety , 1921 
2,4, and 6 weeks’ spray. 
Petiole infection. 
Number 
examined. 
Percentage 
infected. 
None. 
1 
i, 206 
1,120 
1,24s 
1,196 
93*0 
3*3 
i -7 
26. 0 
Bordeaux 4-6-50. 
Bordeaux 2-4-50. 
Lime sulphur i°. 
