148 The Philippine Journal of Science 1922 
as the oranges of Florida origin and some of the Hast Indian 
pummelos. The grapefruits and West Indian limes are affected 
much more seriously, both on the foliage and on the fruits. The 
Satsumas, Valencias, and mandarin oranges are not so severely 
affected. 
To summarize, the injury to Washington navels caused by 
citrus canker is due to: (a) An indeterminable loss, due to a 
decrease in the functioning of infected leaves; (b) a scarcely 
appreciable loss, due to the dropping of fruits affected when 
young; (c) a loss in marketing, due to the blemish on affected 
fruits; (d) a slight loss in weight of cankered fruits; and (e) 
occasional secondary infection with fruit rots, following canker 
infection. 
APPLICATION OF RESULTS 
The reduction in amounts of canker recorded here on the 
Washington navel warrants the statement that a control for this 
disease is possible for hosts of this class of susceptibility and 
for less-susceptible species and varieties. Such a control appears 
to be feasible from a standpoint of costs. For commercial use 
it is recommended that Bordeaux 4—4—50 be used in periods 
of wet weather, while a change to lime sulphur should be made 
in periods of little rainfall. The utmost precaution is necessary 
to avoid increases in insects following copper sprays; for this 
reason an oil emulsion or other scalecide should be added to 
the Bordeaux mixture, probably with every application. 
In the southern United States, where eradication work is 
still in progress, the use of preventive sprays, such as Bordeaux 
mixture with an oil emulsion, for trees adjacent to an infected 
tree will obviously reduce the chances for the spread of infection. 
In the past, formalin solutions have been frequently used; such 
solutions not only are more expensive but, at concentrations not 
injurious to the trees, also have no bactericidal or preventive 
value. 
It also seems reasonable to suppose that lime-sulphur and 
Bordeaux-mixture applications, made for the prevention of citrus 
scab and other diseases, will greatly lessen the chances for can- 
ker infection. 
The spraying schedule used for these experiments in Nagasaki 
Prefecture apparently requires slight changes. The application 
made on August 24 could be advanced to August 15, apparently 
with better results. Should the results warrant, two applica- 
tions could be made during the typhoon period, in August and 
September. These statements of course apply only to Nagasaki 
