CERCOSPORA LEAF SPOT OF AVERRHOA CARAMBOLA 1 
By Colin G. Welles 
Associate Professor of Plant Pathology, College of Agriculture, University 
of the Philippines 
TWO PLATES 
A very serious leaf spot, causing partial or complete defolia- 
tion of Averrhoa carambola Linnaeus has been observed in the 
experimental orchard of the College of Agriculture, Los Banos, 
Philippine Islands. The writer is unable to find any note that 
describes a Cercospora leaf spot on the above-named host. 
Averrhoa carambola is a native of tropical America, but now 
occurs in all tropical countries. It is cultivated for its acid fruits. 
The trees under observation were brought to Los Banos about 
eight years ago from China and have shown fairly normal de- 
velopment since that time. No leaf spotting has been recorded 
on this host by any of the local plant pathologists or collectors. 
The spotting was first noticed about June 25 , 1921 , approx- 
imately at the beginning of the wet season. At this time, 
however, spotted leaves were few in number and the attack was 
scarcely noticeable. 
On July 15, a different condition existed. The trees showed 
partial defoliation, and a careful count showed that 100 per cent 
of the larger leaves were infected with from one to ten lesions. 
At this time it appeared that a thorough spraying would have 
to be resorted to if the trees were to be kept from complete 
defoliation. 
This paper presents studies made upon the disease with 
special stress on the causal organism and control measures. 
SYMPTOMS 
The disease appears as a spotting of the leaves of Averrhoa 
carambola. When young the lesions appear as irregular, yellow, 
chlorotic spots, from 3 to 5 millimeters in the largest dimension. 
These chlorotic areas may coalesce and form a large irregular 
1 The author wishes to express his appreciation for the constructive crit- 
icism of Mr. H. Atherton Lee, of the Bureau of Science. 
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