UNITED STATES DEPARTMENT OF AGRICULTURE 
Contribution from Bare of Entomology. 
L. O. HOWARD, Chief. 
Washington, D. C. 
March 10, 1917 
FUMIGATION OF ORNAMENTAL GREENHOUSE 
PLANTS WITH HYDROCYANIC-ACID GAS. 
By E. R. Sasscer, Collaborator, 
and A. D. Borden, Scientific Assistant. 
CONTENTS. 
Page. 
EN GRO GT CHIOMEr yep rae eee oleae naar 1 | Ventilation after fumigation................. 
Equipment necessary for fumigation........ 2 | Effects of weather conditions on fumigation. . 
Preparation of house for fumigation.......... 3 | Advisability of afumigation box............. 
Method of computing the cubical contents of 
even and three-quarter-span See BNC Soc 
Tim ewor MMM Sa GlOMe ee ees cee te eaiels 
Chemicals required for fumigation........... 
Determining the amount of cyanid to be used. 
Chemical formula to be employed...-.....-.... 
Maxdn cipher chemicals scene rm less seteraane closers 
Number of generators to be employed....... 
IDDAGDUSWIROS. sac apecudoondmoceésausooSsooGoos ede 
VIUN Oa wp 
How insects are disseminated from house to 
Cost of hydrocyanic-acid gas fumigation.... 
IPTEGAUET OIG eos earner a a cre eae eee oc 
Plants and insects fumigated in greenhouses... 
Plants and insects fumigated in fumigation 
DOK sites cide etins com cee eee ccincioe eis amarante cia 
COVAGHUST OTN ere aie SEN eS PR 
INTRODUCTION. 
Hydrocyanic-acid gas, if intelligently employed, is one of the 
cheapest and most efficient methods of controlling thrips, aphids, 
white flies, and various scale insects on plants grown under glass. 
That this method of control has not: been generally adopted is no 
doubt owing to the deadly poisonous nature of the gas if inhaled, its 
disastrous effect on tender plants if improperly used, and the pre- 
Norre.—Hydrocyanic-acid gas was first used against greenhouse pests in 1895 by Messrs.. 
A. F. Woods and P. H. Dorsett (see Circular No. 37, Bureau of Entomology, U. S. 
Department of Agriculture) 
observation. 
in an effort to destroy insects on diseased plants under 
Subsequently others have employed the gas in greenhouse fumigation, but 
with varying success, largely because of inexperience and improper methods of procedure. 
In the earlier experiments in greenhouses conducted by the Bureau of Entomology the 
senior author was assisted by Mr. H. L. Sanford, of the Federal Horticultural Board, 
and by Messrs. 
Industry. 
by Messrs. 
EHugene May, W. R. Lucas, and Charles Keller, of the Bureau of Plant 
The spelling of the botanical names used in this publication has been verified. 
P. L. Ricker and H. C. Skeels. 
CAUTION.—H ydrocyanic-acid gas is colorless and is one of the most deadly poisonous 
gases known. 
It has an odor much like that of peach pits. 
In case of accidental inhala- 
tion of the gas, the person affected should be kept in the open air and required to walk: 
to increase respiration. 
71777°—Bull. 518—17——-1 
