638 
The Philippine Journal of Science 
1920 
held at a temperature varying closely around 12° C., in all cases 
were negative. This was attempted for the reason that it was 
feared that the normal Manila temperatures might be too high 
for positive infection. The result showed that this was not the 
case but the instance is presented as of possible value to a future 
investigator. 
Reinoculations were then made on Washington navel oranges. 
These inoculations were made in two lots; (1) inoculated fruits 
held in a moist chamber with controls, and (2) fruits held 
at the normal laboratory atmospheric humidity of Manila in 
May; the normal humidity in May is not high. The fruits 
were disinfected with alcohol as previously, and both controls 
and fungus inoculations were made with needle punctures. The 
results are shown in Table 2. 
Table 2. — Inoculations on mature Washington navel oranges, with tap water 
for controls, and with pure culture of Phoma citricarpa. 
[Inoculated May 21, 1920 ; date of observation of results, June 9 , 1920 .] 
Fruit No. 
Punc- 
tures. 
Inoculum. 
Conditions of 
humidity. 
Positive 
results. 
1 
20 
Dry laboratory ___ 
Per cent . 
0 
2 
20 
0 
3 
20 
do 
0 
4 
20 
do 
0 
5 
20 
do 
0 
6 
20 
0 
7 - 
20 
Phoma citricarpa _ 
Dry laboratory-.. 
0 
8 
20 
* 65 
9 
20 
» 10 
10 
20 
b 5 
11 
20 
b 25 
12 
20 
do 
b 76 
a Doubtful lesions. b Clearly positive. 
Table 2 shows that under dry atmospheric conditions the 
fungus produces no lesion, or lesions which are very doubtful. 
With increased atmospheric moisture, 35 per cent of the inocula- 
tion punctures were positive; the lesions under such conditions 
were dead black in the center, becoming slightly reddish toward 
the margins and varying in diameter from 1 to 3 millimeters. 
They were in most cases typical black-spot lesions. The fungus 
was reisolated from the positive lesions. Control punctures with 
tap water remained entirely negative and in many cases healed 
so as to be unnoticeable. 
