3 
BULLETIN 1253, U. S. DEPARTMENT OF AGRICULTURE. 
work of Brooks and Cooley 2 , can not cause much new infection if 
the temperature is kept below 50° F. 
Table 4. — Summary, box crop 
by months, 1917 to 192C 
>. 
Month. 
Total 
cars. 
Rots. 
Scald. 
Other 
diseases. 
Disease 
index. 1 
July 
Per cent. 
Per cent. 
Per cent. 
August.. . .. . .. . . 
6 
( 2 ) 
ll.l 
12.0 
September ... .. _. 
October . - - .. ... 
89 
207 
322 
318 
498 
889 
647 
485 
213 
3.8 
5.2 
5.0 
5.8 
6.9 
6.8 
7.6 
8.1 
8.5 
1.3 
2.0 
1.5 
2.1 
( 2 ) 
(*> 
( 2 ) 
( 2 ) 
.( 2 ) 
5.2 
November -- .. - 
( 2 ) 
( 2 ) 
( 2 ) 
3.2 
7.8 
7.0 
6.0 
9.9 
7.7 
6.9 
8.5 
February .... ... 
10.9 
15.0 
14.8 
May 
14.2 
June .. .. 
18.5 
Total or average 
3,674 
6.8 
5.0 
( 2 ) 
12.6 
i See foot note to Table 3. 
2 Less than 1 per cent. 
The proportions of scald before February and of " other diseases" 
after January were less than 1 per cent and are so indicated in the 
table. Delay in the appearance of scald is to be expected every 
year. It never develops early except on Grimes Golden and a few 
other fall varieties. Practical disappearance of " other diseases v after 
January is of no particular significance. These diseases never were 
found in large percentage except in an occasional car; as, for example, 
PER CENT 
DISEASED 
28 
24 
20 
I 6 
I 2 
8 
4 
Disease Index 
Pi 
Scald^S 
'•y 
*^ 
+' 
H 
Rots 
__-vfl-. 
~'T~ 
v 
/ 
\x 
{-Other Diseases 
^ ^* 
\^\ ^ 
- 1 
" 
' 
T"^ 
^ h CD £ r- > u 
fefi Z> => lZj O O UJ 
^3^ -? < co O 2 Q 
CO > 
a * < 
< 5 
Fig. 2. — Barrel crop. Percentages of rots, scald, and other diseases, and disease index, by months, for the 
four crop years, 1917 to 1920, inclusive. The percentages are calculated on the basis of all cars showing 
disease of any kind. 
in August, 1920, when two of the six cars inspected showed an 
average of 8 per cent of bitter-pit and two others 25 per cent each 
of internal breakdown. 
Scald. — Scald first appeared in November, but, calculated on the 
basis of all cars showing disease, was of little importance until 
February, rose decidedly in March, and was at its highest in June. 
It was reported from the largest number of cars in March. 
1 Charles Brooks and J. S. Cooley. Temperature relations of apple-rot fungi. 
V. 8, p. 139-163. 1917. 
In Jour. Agr. Research, 
