150 The Philippine Journal of Science 
spider. *There were slight increases in these troubles following 
the lime sulphur applications. 
9. The injury of citrus canker to the Washington navel orange 
is described in detail, and consists of an indeterminable loss to 
the tree due to a slight reduction in functioning leaf surface, 
a slight loss due to dropping of fruits infected when young, the 
loss due to reduction in market value resulting from the blemish 
on fruits when cankered, a slight reduction in weight of affected 
fruits, and an infrequent secondary infection with fruit rots 
following canker infection. These statements do not apply to 
the more-susceptible limes and grapefruits nor to the less-sus- 
ceptible Mediterranean sweet oranges, Satsuma oranges, lemons, 
mandarin oranges, calamondins, kumquats, or citrons. 
10. It seems reasonable to conclude that, in countries where 
citrus canker is already widespread or universal, a feasible control 
may be obtained upon citrus fruits of the general susceptibility 
of the Washington navel. In regions such as Florida and the 
Gulf States of America, where an attempt is being made to 
eradicate the disease entirely, preventive sprays would materially 
lessen the chances for infection. Formalin 1 to 100, recom- 
mended by Kellerman for this use, is here shown to be entirely 
valueless as a preventive and, previously, as a bactericide; it is 
moreover three times as expensive as a copper spray. Lime sul- 
phur, or Bordeaux mixtures with an oil emulsion, from these 
experiments, would seem to be the preventive sprays most effec- 
tive for this use. 3 
REFERENCES 
1. Gray, Geo. P., and Ryan, H. J. Reduced acidity caused by certain 
sprays. Mo. Bull. Dept. Agr. California, No. 1, 10 (January, 1921) 
11. 
2. KELLERMAN, KarL F. Cooperative work for eradicating citrus canker. 
Yearbook of the U. S. Dept. Agr. (1916) 270. 
3. Lee, H. ATHERTON. Action of some fungicides on the citrus-canker 
organism. Philip, Journ. Sci. 17 (1920) 325. 
4, LEE, H. ATHERTON. Citrus-canker control, a progress report of ex- 
periments. Philip. Journ. Sci. 19 (1921) 129. 
5. PeuTier, GEoRcE L. Influence of temperature and humidity on the growth 
of Pseudomonas citri and its host plants and on infection and de- 
velopment of the disease. Journ. Agr. Res. 20 (1920) 447. 
6. VILLEDIEU G., M. and Mme. De la non-toxicité du cuivre pour le mildiou. 
Compt. Rend. Acad. Sci. 172 (1921) 335. 
7. WINSTON, J. R., and Futon, H. R. The field testing of copper-spray 
coatings. Bull. U. S. Dept. Agr. 785 (1919) professional paper. 
