19, 2 Lee: Citrus-canker Control 145 
It would seem, then, that such preventive sprays have, to some 
extent, reduced the amounts of infection. In the light of the 
writer’s disinfectant tests(11) it-is difficult to ascribe the cause 
for this reduction unless it be to the excesses of copper precip- 
itants applied, or even possibly to the mechanical effects of 
the spray deposits on the foliage. 
The criticism of the results, from a commercial viewpoint, 
would be of course that nine spray applications are not eco- 
nomically feasible. It should be noted however that, theoret- 
ically, control should more nearly approach the absolute, year 
after year, since with the gradual prevention of canker infec- 
tion by preventive coatings there is also a gradual reduction 
in the sources of infection. This would reduce to some extent 
the necessity for such frequent spray applications. It would 
seem probable also that, with greater knowledge of the climatic 
peculiarities of the locality and the growth periods of the dif- 
ferent varieties, the number of spray applications would be re- 
duced somewhat. This can only be determined by a continuation 
of the experiments, which will be reported upon in further 
publications. 
THE CONTROL EXPERIMENTS AT LAMAO 
DESCRIPTION OF ORCHARD CONDITIONS 
In these experiments no effort was made to compare the value 
of the ‘different spray mixtures used, the main purpose being 
to determine whether or not canker control was feasible by any 
and all means. The experiments were carried on in three or- 
chards of the Lamao experiment station of the Philippine Bureau 
of Agriculture. These orchards consist of collections of the 
common horticultural varieties of Citrus species grown in the 
United States and Japan, usually two individuals representing 
each variety.® 
The division of these orchards into spray plats in such a way 
as to include individuals of each species in each plat was difficult ; 
however, an attempt was made to make each plat representative. 
*These collections are mainly the work of Mr. P. J. Wester, agricul- 
tural advisor, Philippine Bureau of Agriculture. The collections are 
very extensive and contain a great number of the commonly grown citrus 
varieties of America as well as many Japanese-grown varieties. In ad- 
dition, Mr. Wester has introductions from India, Siam, China, and Aus- 
tralia, as well as a very extensive collection of the native Philippine 
fruits. The writer is greatly indebted to Mr. Wester for his very hearty 
coéperation in the identification of obscure varieties, the use of his card 
indexes, and all matter relating to his collections. 
1807822 
