19, 2 Lee: Citrus-canker Control 151 
Table 11 shows that in all cases of susceptible trees, a consider- 
able reduction in the amounts of citrus canker took place during 
the year. 
The behavior of the trees of the Tahiti lime is noteworthy. 
Both of these trees were in actively growing condition and well 
exposed to infection; however, they exhibited a very moderate 
susceptibility to canker, and control was very easily obtained. 
Other trees of the Tahiti lime have been under observation at 
Lamao and have exhibited the same slight susceptibility to 
canker. This is all the more peculiar, as Wester(19) also has 
pointed out, since for the most part lime varieties are extremely 
susceptible. 
The behavior of the Triumph grapefruit is also noteworthy ; 
as grown at Lamao, it apparently has a less degree of susceptibil- 
ity to canker than have the other American-grown grapefruit 
varieties. The lemon varieties as shown in the table are but 
moderately susceptible and they responded readily to the control 
methods employed. 
PLAT IV, ORCHARD A, LAMAO 
The treatment and results were much the same on this plat 
as on plats I and III. 
Of interest from this plat was the ease of control of the Limon 
Real, a Philippine, lemonlike fruit. Of greater interest in the 
United States is the behavior of the Mediterranean sweet orange 
varieties, the Jaffa, St. Michael, and Ruby. The susceptibility 
of these varieties is very slight, and they responded very 
quickly to the control methods employed. 
PLAT VI, ORCHARD B, LAMAO 
It was intended that this plat should be sprayed continuously 
with ammoniacal copper carbonate solution as a test of that 
Spray as compared with other mixtures. 
At the beginning of October, after two applications, it was 
apparent that this spray was having little effect upon citrus 
canker, in as much as new infections were appearing continuous- 
ly. Spraying was abandoned, therefore, and the plat became a 
check upon the other plats in Orchard B, for the next spraying 
season, 
Table 12 shows that on a few trees in this plat the amounts 
of canker decreased; on the other hand, there was an equal 
number of cases where the amounts of canker increased. Ex- 
amination of the table enables one to compare the canker condi- 
