PINK DISEASE OF CITRUS 
By H. Atherton Lee and Harry S. Yates ‘ 
(From the Bureau of Plant Industry, U. S. Department of Agriculture, 
Washington, D. C., and the Botanical Section of the Biological 
Laboratory, Bureau of Science, Manila, P. I.) 
seven plates and two text figures 
During field work in 1917 an apparently serious stem and 
branch disease of citrus trees was discovered. Subsequent and 
more extended observation has indicated that the disease may 
cause the death of the affected branches or even of the whole 
tree. The spread of the disease and subsequent destruction of 
the trees during the rainy season was found to be very rapid. 
Specimens of diseased material in various stages were collected, 
and examination showed the organism responsible to be the pre- 
viously well-described Corticium salmonicolor B. & Br.^ Though 
this species of Corticium is known to cause very serious diseases 
of Hevea brasiliensis (HBK) Muell., Theobroma cacao Linn., 
Coffea sp., Thea sp., and other plants in the Orient, and has 
previously been reported upon Citrus, it has apparently not been 
known to cause an important disease of the latter host. Since 
the disease at present appears to be localized in its occurrence 
and as its spread over the Islands may involve serious damage 
not only to Citrus but also to cacao, coffee, rubber, and possibly 
* The writers wish to express their appreciation to Mr. E. Bateson, 
director of agriculture and mycologist for the Government of British 
North Borneo, for assistance and many courtesies extended to the junior 
writer, while on a recent visit to that country. The senior writer is 
indebted to Col. Adriano Hernandez, director, and Mr. S. Apostol, chief, 
division of plant industry, Philippine Bureau of Agriculture, for their 
kindness in making available to him opportunities for field work. He 
wishes to thank also Dr. Alvin J. Cox, former director, and Mr. E. D. 
Merrill, botanist, of the Philippine Bureau of Science, for many courtesies 
and the facilities of the botanical laboratories of that bureau. 
“ The identification of Corticium salmonicolor B. & Br. is based, not 
only upon a careful study of the organism and a comparison with the 
published descriptions and figures, but also upon comparison of material 
of Corticium salmouiicolor B. & Br. collected upon Hevea brasiliensis 
(HBK) Muell. and on Annona sp. in British North Borneo where an 
opportunity was found to observe pink disease as it occurs in the field on 
Hevea brasiliensis (HBK) Muell., Hibiscus sp., and Annona sp. 
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