128 The Philippine Journal of Science 1922 
by typhoons; but, when such storms occur, the winds are usually 
accompanied by rain and conditions are extremely favorable 
for canker dissemination as well as infection. 
The seasons in Nagasaki Prefecture, from the viewpoint of 
activity for canker dissemination and infection, may be approxi- 
mately grouped as shown in Table 3. 
TABLE 3.—Showing climatic periods in Nagasaki Prefecture, favorable or 
unfavorable for citrus-canker development. 
November, December, January, February, March, and April: 
Temperatures usually below 20°C. Rainfall slight; canker dissem- 
ination and development very slight, if at all active. No foliage or 
fruit development of host plants during the period November to 
March. 
May: , 
Temperatures usually below 20°C. and rainfall usually low. No growth 
of foliage during this period. 
June and July: 
Temperatures increased and favorable. for canker development. Rain- 
fall increased, frequently intense, favorable for canker development. 
The fruit and foliage of the host plant growing actively and favor- 
able for canker infection. 
Late July and early August: 
Temperatures favorable for canker development, but rainfall slight; 
under ordinary seasonal conditions not a period for serious canker 
development. 
August and September: 
A period of possible typhoons with high wind velocities and intense 
rainfall, favorable for the dissemination and development of citrus 
canker. There is little foliage growth at this time but fruit develop- 
ment is taking place and the fruit tissues are in a susceptible stage. 
October and November: » 
The temperatures become lower very abruptly in usual years; rainfall 
also is very slight. The fruit is so nearly mature as to be no 
longer susceptible, and no foliage growth takes place at this season. 
This is a period in which canker activity may be disregarded. 
With this perspective of the seasonal conditions, the control 
campaign was outlined to apply protective spray coatings during 
the critical seasons of the nyubei in June and the period of 
probable typhoons in late August and September; how this was 
done will be shown in detail in the following pages. 
EXPERIMENTAL METHODS AND ORCHARD CONDITIONS 
The orchard conditions can best be appreciated by an extract 
from the writers’ notebook written before the experiments were 
undertaken. 
