6 



FARMERS-' BULLETIN 862. 



Table I sets forth the general resuMs 1 of experiments made to test 

 the value of fumigation. The work ,was performed during the years 

 from 1909 to 1917, under -the climatic conditions normal to orchard 

 fumigation in southern "California. . 



TABLE I. Result? of futniyution iritli hydroqyanic-acid <j<ix ayainxt tltc common 



. .' mcalybmj. 



\. 8-OUNCE Ui S. ARMY DUCK TEXT. 

 SINGLE CHARGE. 



REPEATED CHARGE UNDER SAME TENT. 



B. GAS-TIGHT TENT. 



C. GAS-TIGHT BOX OF 100 CUBIC FEET CAPACITY. 



i This schedule is given on page 34 of Bulletin No. 90 of the Bureau of Entomology, U. S. Department 

 of Agriculture. 



These results show the ineffectiveness of single-dosage fumigations 

 under army duck tents, even where excessive dosages are used. Ke- 

 peated charges give better results but can not be recommended except 

 in the case of a limited number of trees where other control measures 

 are not readily available, or where cost and. possible injury are sec- 

 ondary to immediate cpntrpL ^Since 8-ounce United States Army 

 duck retains hydrocy-anic-acid gas better than any other cloth of 

 which fumigation tents are constructed 'at present," "results equally 



