FUMIGATION OF CITRUS TREES. 
31 
The inaccuracy of such a method is at once apparent. Measure- 
ments made after many estimators have shown that the most careful 
are very irregular in their scheduling. No one has been found who 
does not at times vary as much as 50 per cent in dosage estimates 
for trees containing exactly the same cubic contents after being 
covered with tents. 1 This variation in the scheduling of an indi- 
vidual fumigator is not all, but the general average dosage used 
by one man has 
frequently been 
one-fourth to one- 
half more and 
sometimes even 
twice that used by 
another for the 
very same insect. 
This chart of dos- 
age for the trees in 
an orchard is taken 
into the field at 
night. Before dos- 
ing a row of trees 
the common meth- 
od is to first meas- 
ure out the dosages 
for the trees in this 
row into small cans 
and pitchers, which 
are placed in a 
hand tray, as shown 
in figure 8. This 
tray is then carried 
from one tree to the 
next down the row. 
The water is carried in a pail and measured at each tree. The 
instruments used for measuring the water have been found to vary 
all the way from graduated dippers to quart pitchers or old tin cans. 
Under this old method the general results secured by a few of the more 
careful and expert fumigators have been fairly good. However, the 
work in the majority of cases has been irregular and poor. This old 
system is rapidly sinking into disuse, being replaced by an improved 
procedure which has resulted from the present investigations. 
Fig. 8. 
-Man carrying tray and water bucket as practiced under old 
system of fumigation. (Author's illustration.) 
i See Bui. 79, Bur. Ent., U. S. Dept. Agr., pp. 23-24, 1909. 
