June, ’18] 
QUAYLE: CYANIDE FUMIGATION 
297 
schedules are not correctly calculated for trees of extreme shapes. 
But from field experience, we are also aware of cases of unsatisfactory 
results on the insects with low broad lemon trees, and, on the other 
hand, complaints of too much injury to the tree in the case of tall 
orange trees. The discrepancy in our present dosage schedules for 
trees of different shapes has been pointed out by Woodworth, and he 
has proposed new schedules. 1 These schedules differ from the ones 
now in use chiefly in the fact that the larger trees receive a greatly in¬ 
creased dosage. This increase amounts in some cases to as much as 
40 per cent, which dosage, the writer believes, cannot be used with 
safety to the trees in general practice. 
Tabulation op Data Concerning the Form “Trees” Used in These Experiments 
High Tree Low Tree 
31 ft. x 31 ft. 22 ft. x 44 ft. 
Tape circumference. 31 ft. 44 ft. 
Tent circumference. 97 ft. 69 ft. 
Tent surface. 757 sq.ft. 380 sq.ft. 
Ground surface. 78.5 sq.ft. 154 sq.ft. 
Total surface. 835.5 sq.ft. 534 sq. st. 
Volume. 857 cu.ft. 717 cu.ft. 
It will be seen from the table that the high tent is greater in volume 
by 140 cubic feet, and that the tent surface is greater by 377 square 
feet, the two factors that determine dosage. Consequently, the high 
tree should receive more cyanide than the low tree, but with our present 
schedules, these two trees receive the same amount of cyanide. This 
is partly because the basis of calculation is a geometrical figure corres¬ 
ponding to the shape of the tree, which does not take into account the 
variation in tent surface of differently shaped trees. The higher the 
tree, the greater, proportionally, is the tent surface when the tent is'an 
octagonal sheet. The actual tent surface is determined by one dimen¬ 
sion only, namely, the distance over the tented tree. 2 
In the high tree (31 ft. x 31 ft.) the circumference, as determined by 
the tape, or the geometrical figure, is 31 feet, but if the tape followed in 
and out of the folds of the same tent at the ground the distance would 
be 97 feet, or a difference of 66 feet. In the low tree (22 ft. x 44 ft.) 
measured in the same way, there is a difference of only 25 feet between 
the tape circumference and the actual tent circumference. Conse¬ 
quently, there is more tent area occupied by the folds in a tall narrow 
tree than in a low broad tree. Some of the folds may fit closely 
enough to prevent the entrance of much gas, but many of the folds 
1 Woodworth, C. W. New dosage tables. Cal. Agr. Exp. Sta. Bull. 257, p. 
10-15. 1915. 
2 Morrill, A. W. Fumigation for the citrus white fly. U. S. D. A. Bur. Ent. 
Bull. 76, p. 39. 1908. 
