186 The Philippine Journal of Science 1921 
as follows: Liquor cresolis compositus, 1 quart; kerosene, 3 
quarts; and water, to make 50 gallons. 
A sticker was used in many instances in an attempt to cause 
the copper sprays and lime sulphur to adhere to the foliage for 
the greatest length of time possible. This sticker consisted of 
2 pounds of resin, dissolved with heat in a solution of 1 pound 
of sodium carbonate in 1 gallon of water. The sticker was used 
in these experiments in the ratio of 1 quart of the mixture to 
50 gallons of the spray mixture. 
The removal of the sources of canker infection was obtained 
in some cases by pruning out twig and limb cankers. Another, 
somewhat drastic method was used in a few cases of trees 
with heavy foliage infections. A solution of formalin was pre- 
pared which would partially burn the citrus foliage; leaves with 
canker infections were sometimes already weakened, and these 
dropped after such a drastic spray, while normal leaves in many 
cases would survive this treatment. A 1 to 80 formalin solution 
was used for this purpose on sweet orange, grapefruit, and 
mandarin orange trees with some degree of success. Such a 
concentration was, however, too strong for lime and lemon trees, 
and almost complete defoliation would follow on those hosts. 
The use of formalin solutions for this procedure was closely 
related to the sunlight, conditions; on rainy days or toward 
nightfall the formalin would not evaporate as rapidly as in direct 
sunlight and greater injury would result. The use of a spray 
solution for this purpose was called a clean-up spray, in contra- 
distinction to the term preventive spray. 
It was also attempted to secure the growth of new foliage 
during climatic seasons unfavorable to the development or dis- 
semination of citrus canker. Such growth was secured by 
employing the pruning procedures at the end of the rainy season 
so that new growth stimulated by the pruning came out in the 
dry season. Maintenance of foliage growth was also secured in 
the dry season by irrigation. 
The test of spray mixtures was made along two lines; namely, 
in connection with the pruning and the stimulation of growth 
measures, at Lamao, Bataan, Philippine Islands; and the efficacy 
of spraying alone, without pruning or other measures, was tested 
at Los Banos, Laguna, Philippine Islands. 
THE SPRAYING EXPERIMENTS AT LOS BANOS 
DESCRIPTION OF ORCHARD CONDITIONS 
The orchard at Los Bafios is maintained by the College of 
Agriculture of the University of the Philippines and consists of 
