COMPARATIVE STUDY OF PHYTOPHTHORA FABERI ON 
COCONUT AND CACAO IN THE PHILIPPINE 
ISLANDS. * 1 * 
Otto August Ranking 3 
Formerly Collaborator , Office of Crop Physiology and Breeding Investigations , Bureau 
of Plant Industry , United States Department of Agriculture; Plant Pathologist Philip - 
pine Agricultural Experiment Station; and Professor of Plant Pathology , College of 
Agriculture , University of the Philippines 
INTRODUCTION 
Each year in the Philippine Islands, severe losses result from coconut 
budrot and from blackrot and canker of cacao. In 1919, the writer (7) 3 
produced evidence indicating that the organisms causing both diseases 
were identical. These studies have been continued, and detailed cross 
inoculation experiments, comparisions of parallel cultures, and more 
complete physiological and morphological studies have been made. 
Coconut budrot is a serious disease of the coconut (Cocos nucifera), 
affecting the single terminal bud of the tree. Throughout the world 
various organisms, including bacteria and fungi, have been considered 
responsible for the disease. In the Philippine Islands there are appar¬ 
ently two types of budrot—the really infectious type caused by a Phy- 
tophthora, and a secondary type following some injury such as beetle 
injury and caused primarily by the invasion of bacteria in the weak¬ 
ened tissue. The earliest symptoms of the infectious type are usually 
the production of rows of dark-brown spots on the newly unfolded 
leaves. Later developed leaves then show a severe leaf blighting. 
Finally, the central group of folded leaves dies and turns brown, indicat¬ 
ing the death of the growing point. The bud may not be killed until 
after 12 months from the time of the first leaf spotting. The usual period, 
however, is from 2 to 3 months. The fringe of older, healthy, green 
leaves remains on the tree until it dies a natural death. Infected trees 
are stunted (PI. 4, B) and the nuts do not develop. Internal symptoms 
are characterized by a browning of the folded leaves above the growing 
point. A white mycelial felt may or may not be present on these young 
leaves. From the growing point, downward and to the sides, the organ¬ 
ism advances for a short distance into the woody parts, where the limits 
of its advance are marked by a dark red to brownish line (PI. 1, A). In 
advanced cases, after the entrance of bacteria, the soft region about the 
growing point is changed to a semiliquid, ill-smelling mass. 
The blackrot of pods and the canker of cacao (Theobroma cacao) is 
widely distributed throughout the world in the cacao growing regions. 
In the Philippines, it has been reported as causing severe losses (6, p. 
192-196). The fruit is attacked at any stage of its development. 
Usually the greatest damage is done to the young fruits. At first a 
minute black spot is developed on the infected part. This spot gradually 
1 Accepted for publication May sr, 1923. Presented to the graduate school of the University of Wisconsin 
in partial fulfillment of the requirements for the degree of doctor of philosophy. 
1 Plant pathologist of the United Fruit Co. in Honduras and Guatemala. 
* Reference is made by number (italic) to "literature cited." p. 384. 
Journal of Agricultural Research. 
Washington. D. C. 
afr 
Vol. XXV, No. 6 
Aug. xx. 1923 . 
Key No. G~3*4 
