24 
BULLETIN 571, U. S. DEPARTMENT OF AGRICULTURE. 
trees made practically the same amount of growth during the course 
of the season. 
Further fumigation experiments were conducted during March, 
1916, and are reported in Table XXI. Only badly infested pecan 
twigs were used in these experiments, and after being fumigated, 
they were placed in water bottles in order to insure proper develop- 
ment of the buds. 
Table XXI — Fumigation experiments on larvae of the pecan leaf case-bearer at Mon- 
ticello, Fla., in 1916. 
Experi- 
Num- 
Date of 
ment 
ber of 
Treatment. 
fumiga- 
Results. 
Remarks. 
No. 
twigs. 
tion. 
1916. 
I 
12 
Fumigated for 1 hour with i ounce 
Mar. 4 
Larvae emerged 
All buds destroyed 
of sodium cyanid » per 100 cubic 
from hibernac- 
. by larvae. 
feet. 
ula. 
II 
12 
Fumigated for 1 hour with % ounce 
of sodium cvanid > per 100 cubic 
feet. 
Mar. 3 
do 
Nearly all buds 
were destroyed 
by larvae. 
III 
12 
Fumigated for 1 hour with 1 ounce 
...do.... 
A number of larvae 
. Some buds were 
of sodium cvanid l per 100 cubic 
emerged from 
damaged bv 
feet. 
hibe macula. 
larvae. 
IV 
12 
Fumigated for 1 hour with 1 ounce 
of sodium cvanid 2 per 100 cubic 
feet. 
...do.... 
do 
A good many buds 
destroyed by 
larvae. 
V 
12 
Fumigated for 1 hour with H ounces 
...do.... 
No larvae emerged 
Buds didnotunfold 
of sodium cvanid * per 100 cubic 
from hiber- 
well. 
feet. 
nacula. 
VI 
12 
Check; not fumigated 
...do.... 
Larvae emerged 
All buds were de- 
from hibernae- 
ula. 
No larvae emerged 
stroyed by larvae . 
VII 
15 
Fumigated for 1 hour with \\ ounces 
Mar. 29 
No injury to buds 
of sodium cvanid 1 per 100 cubic 
from hibernac- 
from fumigation. 
feet. 
ula. 
VIII 
15 
Fumigated for 1 hour with 2 ounces 
of sodium cvanid x per 100 cubic 
feet. 
Check; not fumigated. 
...do.... 
do 
No injury to buds 
from fumigation. 
IX 
15 
...do.... 
Larvae emerged 
All buds destroyed 
from hibernac- 
by larvae. 
ula. 
1 Used formula 1-2-3. 
2 Used formula 1-1-3. 
It will be noted in Table XXI that strengths of sodium cvanid 
of i, f, and 1 ounce per 100 cubic feet failed to destroy the larvse 
after one hour of exposure, while strengths of 1^ and 2 ounces per 
100 cubic feet killed all larvse. It is to be regretted that in these 
experiments a strength of 1J ounces was not used, as it was found 
that while 1 ounce was not enough, 1 J ounces destroyed larvas while 
in the winter cases. Although the maximum strength used (1^ 
ounces per 100 cubic feet of space) is considerably in excess of that 
commonly employed in the fumigation of ordinary nursery stock, 
these experiments indicated that, while in a dormant condition, the 
pecan was perfectly capable of enduring the greater strength without 
injury. 
In fumigation for the pecan leaf case-bearer materials should be 
used according to the following formula: 1-1 J-2. This means 
that 1 ounce (avoirdupois) of sodium cyanid, 1J fluid ounces of 
