April, ’20] 
PETERSON: PEACH-TREE BORER 
205 
trees were treated during May, and June, 1919, and September, 1918, 
with one half and one ounce and they were not affected. It is probable 
that November is too late in the year to safely treat trees with NaCN, 
particularly when applied in liquid form. In all our experiments with 
sodium cyanide a one ounce treatment (liquid or granular form) has 
not seriously injured or killed five- to ten-year-old trees when applied 
in May, June, September, or October. 
Table V. The Effect of Sodium Cyanide on Peach Trees Two to Four Years of Age, 
1917-19 
Treatment 
Date 
Soil 
Age of 
trees 
Normal 
trees 
Injured 
trees 
Dead 
trees 
*§ oz. dry 
June 4, T9 
Sand loam 
3 
6 
2 
2 
*1 oz. dry 
June 4, T9 
3 
3 
2 
5 
5 oz. to 1 gal. 
July 23, T7 
2 
2 
0 
0 
| oz. to 1 gal. 
July 23, T 7 
2 
2 
0 
0 
1 oz. to 1 gal. 
July 23, T7 
2 
1 
1 
0 
2 oz. to 1 gal. 
July 23, T7 
2 
1 
0 
1 
§ oz. to 1 gal. 
July 23, T7 
4 
2 
0 
0 
f oz. to 1 gal. 
July 23, T7 
4 
2 
0 
0 
1 oz. to 1 gal. 
July 23, T7 
4 
2 
0 
0 
2 oz. to 1 gal. 
July 23, T7 
4 
1 
1 
0 
* Trees in this orchard (Middletown, N. J.) severely injured by winter kill (1917-18). 
Table V shows the results of a few experiments with two- to four- 
year-old trees. The results indicate that healthy trees will stand one 
half to three quarters ounce of sodium cyanide without injury. Trees 
that have been weakened by winter kill or heavily infested with borers 
may be injured or killed by these strengths. 
When sodium cyanide injures the trees the leaves and fruit wilt. The 
leaves gradually turn yellow and drop off. The behavior of an injured 
tree is somewhat similar to trees injured by drought. Injury, due to 
applications made during May and June, usually makes its appearance 
a week or two after the material is applied. In some instances the 
injury may not show for several weeks. Trees injured by heavy doses 
of sodium cyanide in September, October, or November, do not always 
show their injured condition at the time the leaves and flowers appear 
the following season. The trees may give rise to normal leaves and 
flowers and then later in the season (June and July) the leaves and fruit 
may show a wilted condition. This wilted condition may exist several 
weeks before the trees die. 
Sodium Cyanide in the Soil 
So far as known the peach-tree borers are killed by the fumes arising 
from the sodium cyanide. The salt undergoes rapid decomposition 
after it is placed in the soil. One cannot detect an odor of cyanide in 
the soil three weeks after a one ounce application has been made and a 
