DAYLIGHT FUMIGATION, COST OF APPLICATION 87 
Especially is this true of Los Angeles, Orange, and 
San Diego counties, where ordinarily an orchard is 
fumigated but once a year. In any of these counties 
from October until March is considered the best time. 
During this period the scale is young and will yield 
quite readily to treatment by fumigation. 
‘“ As fumigation for red scale seems to be equally 
effective at all times of the year, in order to incur the 
least damage to the grower, in the way of knocking off 
fruit, etc., also to avoid rainy weather and north 
winds, we have made a practice in Riverside County of 
doing the greater part of the fumigation between the 
months of May and December. ‘This period embraces 
our warmest weather. In this connection I wish to 
refer to a matter that has evidently escaped the atten- 
tion of the advocates of daylight fumigation. During 
our summer months we have periods, sometimes ex- 
tending over many days, when the mercury will range 
in the nineties. With a temperature of from go to 95 
degrees we are quite sure that by enclosing a tree 
under an air-tight tent for the time required for fumi- 
gation, which is from 40 to 45 minutes, the tempera- 
ture under the tent would be increased from 25 to 30 
degrees. Add to this the increased heat caused by 
generating the chemicals, which would be perhaps 
to degrees more, and the resulting temperature would 
very likely do harm. It is well known that a citrus 
tree will not stand a temperature of 135 degrees for 
any length of time without serious results. We know 
from actual observation that the action of sunlight upon 
hydrocyanic acid gas has a scalding or burning effect 
upon foliage. Practically all of the damage ever done 
