Vol. IX Washington, D. C., April 2, 1917 No. 1 
A NEW BACTERIAL CITRUS DISEASE 1 
By H. Atherton Bee, 2 
Scientific Assistant, Division of Plant Pathology, University of California 
Agricultural Experiment Station 
INTRODUCTION 
During the last few years a disease of Citrus trees, and particularly 
of orange trees, has been brought repeatedly to the attention of differ¬ 
ent members of the Agricultural Experiment Station staff of the Univer¬ 
sity of California. In some respects the trouble resembles frost injury, 
so that many growers, believing that it was due to frost, did not appre¬ 
ciate its full significance. Occasionally material has been brought to the 
laboratories of plant pathology at Berkeley and at Riverside; but such 
material has been old and dried and has given no clue to the real cause. 
In March, 1916, Dr. J. E: Coit, of the division of citriculture, called 
attention to this disease and discussed its seriousness. 8 Since he found 
no similar disease described in literature, he called it “Citrus blast,” a 
new disease. 
DESCRIPTION OF THE DISEASE 
During the rainy season of California, usually about the middle of 
January, the disease is first noticed. Young leaves are found to be 
dropping off, sometimes leaving single twigs or at other times whole 
branches of twigs bare of leaves. On examining more closely, black, 
discolored areas are noted on the leaves; such areas are found most 
commonly at the junction of the leaf blade and the wings of the 
petiole. Plate A, figure 3, shows such lesions. The affected parts have 
a water-soaked appearance, and the whole leaf loses its rigidity and hangs 
limply from the branch. Less commonly such water-soaked lesions 
appear near the tips of the leaves. 
1 Approved for publication by Thomas F. Hunt, Director, California Agricultural Experiment Station. 
* Now Scientific Assistant, Fruit Disease Investigations, Bureau of Plant Industry, United States De¬ 
partment of Agriculture. 
The author wishes to express appreciation and thanks to Prof. Ralph E. Smith, of the University erf 
California, for direction of this work; also to Dr. William A. Setchell, of the same university, for the 
translation into Latin of the description of the organism. 
®Coit, J. E. Citrus blast—a new disease in California. In Univ. Cal. Jour. Agr., v. 3, no. 6, p. 234-235, 
illus. 1916. 
Journal of Agricultural Research, 
Washington, D. C 
hp 
(*> 
Vol. IX, No. 1 
Apr. 2, 1917 
Key No. Cal.—10 
