750 
The Philippine Journal of Science 
The ten diseased trees that were used were not especially 
selected for the purpose. A count of the older leaves showed 
that 100 per cent on all trees were infected. 
Six of the trees were sprayed thoroughly with Bordeaux mix- 
ture and were examined after two weeks. The sprayed trees 
were not defoliated to a great extent and the number of leaves 
were in striking contrast with those on the unsprayed trees. 
Plate 1 shows the results very distinctly. 
Counts were made of diseased leaves from sprayed and un- 
sprayed trees at this time. The number of leaves exhibiting 
young lesions on the sprayed trees was 20 per cent of all ob- 
served. One hundred per cent of the leaves from unsprayed trees 
were parasitized, showing from one to four young lesions and 
frequently as many old ones. The number of new infections, 
then, was reduced 80 per cent due to the Bordeaux mixture 
application. Frequent heavy rains gave optimum conditions 
for infection. 
By August 1 a different condition existed. The trees that had 
been sprayed were still holding their less seriously diseased 
leaves. The unsprayed trees had become entirely defoliated and 
had put forth new leaves, which by August 8 had not developed 
any lesions. 
This experiment conclusively proves that Bordeaux mixture, 
if applied carefully, will give perfect control. If the spray is 
used once every two weeks until the disease disappears and if 
the fungus does not attack other hosts, eradication should be 
easily accomplished. 
SUMMARY 
1. A very serious Cercospora leaf spot was found in the ex- 
perimental orchard of the College of Agriculture, Los Banos, 
Philippine Islands, on Averrhoa carambola. 
2. It attacks leaves and perhaps fruits. The young leaf lesions 
are yellow, later turning grayish brown, and finally either falling 
out or causing the death of the leaf. 
3. Averrhoa bilimbi is not attacked. 
4. The leaf spot threatens the life of the trees in the orchard 
by repeated defoliation. 
5. The name Cercospora averrhoi sp. nov. is suggested to 
designate the causal organism. 
6. Control by spraying with Bordeaux mixture is very effi- 
cient. By repeated sprayings every two weeks the disease can 
be efficiently controlled. Complete eradication would seem to 
be possible. 
