STUDIES IN GREENHOUSE FUMIGATION WITH HYDRO¬ 
CYANIC ACID: PHYSIOLOGICAL EFFECTS ON THE 
PLANT 1 
By William Moore, Head of Section of Research in Economic Zoology , and J. J. Will a- 
man, Assistant Chemist , Minnesota Agricultural Experiment Station 
INTRODUCTION 
In a previous paper (15) 2 the relationship between temperature and 
moisture to the degree of injury to plants fumigated with hydrocyanic 
acid was considered. The next step in the investigation has been to 
determine the action of the gas on the tissues of the plant. Little infor¬ 
mation on this point is to be found in the literature. In fact, some 
investigators have considered the injury to be not due to hydrocyanic 
acid, but to hydrochloric-acid fumes generated from sodium-chlorid 
impurities in the commercial cyanid (24). The reactions of hydrocyanic 
acid on isolated compounds have received considerable attention, but not 
from the standpoint of injury to plants during fumigation. The object 
of this paper is to show that hydrocyanic acid penetrates the tissues and is 
responsible for certain disturbances in the metabolism of the plant which 
may result in injury or even death. 
EVIDENCE OF THE PENETRATION OF THE GAS 
In order to demonstrate the actual presence of the hydrocyanic acid 
in the plant, chemical analyses were made at various intervals after 
fumigation. 
From 60 to 130 gm. of tomato plants, usually 8 to 20 plants, were ground 
in a food chopper, suspended in a Kjeldahl flask in 300 c. c. of 5 per cent 
tartaric acid, and slowly distilled into a little 5 per cent sodium hydroxid 
until 100 c. c. of distillate were obtained. The cyanid in this distillate 
was then estimated by the method of Viehoever and Johns (22). A por¬ 
tion of the sample of tissue was used for the determination of dry matter. 
The results are given in Table I. It is evident that there is an appre¬ 
ciable amount of cyanid absorbed, and that this amount is proportional 
to the injury produced. These figures are only comparative, since it is 
impossible to recover quantitatively the hydrocyanic acid contained in a 
plant tissue (1, 23). The acid disappears within a few hours after 
fumigation; and it is during this period, as will be shown later, that 
certain physiological disturbances are evident. 
1 Published, with the approval of the Director, as Paper No. 69 of the Journal Series of the Minnesota 
Experiment Station. 
2 Reference is made by number to “ Literature cited,” p. 336-338. 
Journal of Agricultural Research, 
Washington, D. C. 
kl 
(319) 
Vol XI, No. 1 
Nov. 12, 1917 
Key No. Minn.—21 
