134 
The Philippine Journal of Science 
1921 
Alabama. His conclusions are best obtained by a direct quota- 
tion from his publication : 
All visible signs bf canker were carefully removed from the trees prior 
to the application of the mixtures. Bordeaux mixture, Bordeaux mixture 
and bichlorid of mercury (12 tablets in 3 gallons), Bordeaux mixture and 
formaldehyde (1:100), and a Bordeaux and lead arsenate mixture were 
employed. Applications were made on March 26, April 29, and May 14, 
and no new infections had developed on any of the sprayed or unsprayed 
trees by the last named date. On May 27, however, new infections were 
apparent and were equally numerous on sprayed and check trees. 
These results of course apply only to the grapefruit, the most 
susceptible host. 
Doryland (6) has reported successful results of spraying ex- 
periments against citrus canker upon seedling trees of calamon- 
din, mandarin, and sweet-orange varieties in nursery rows at 
the Singalong experiment station in Manila, Philippine Islands. 
He found that spraying with Bordeaux mixture 4-6-50 met with 
little or no success when used in the rainy season, but later 
he obtained favorable results by using formalin in a 1 to 
100 solution at ten-day intervals. Doryland does not give his 
dates of spraying, but a survey of his statements as to time of 
application leads to the conclusion that his favorable results with 
formalin were obtained in the dry season, when active dissemina- 
tion of citrus canker is limited. His later report (7) states that 
applications at ten-day intervals of Bordeaux mixture 4-6-50, 
plus formalin to make a 0.4 per cent solution, were able to rid 
the plants of canker in four months. His spraying was begun 
January 29; therefore, four months would bring his experiments 
to a conclusion on May 29. January, February, March, April, 
and May are dry months in the Manila Bay region, as Table 1 
has shown. By using creolin-formalin emulsion, Doryland was 
able to decrease canker during the first four months, but during 
the fifth month there was a bad increase in canker. The fifth 
month would be June, which has a very heavy rainfall. Thus 
it would seem as if Doryland’s data may be taken to show that 
canker can be controlled in the dry months, but that his results 
do not apply to the rainy season when canker dissemination 
and development are active. This conclusion would bear out 
Wester’s result. 
Doidge(5) reports that citrus canker was controlled with 
Bordeaux mixture 4-4-50 under conditions in the Transvaal, 
where there is a long dry season. She does not give the host 
upon which the control was obtained. 
Kellerman(8) advised spraying healthy trees with a 1 per 
