4 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 



parties, including contractors, associations, county horticultural 

 commissions, and private individuals, owned approximately 5,150 

 tents on June 1, 1910, the date on which the securing of these data 

 was completed. 



In order to ascertain the extent to which fumigation is now prac- 

 ticed, as well as the tax which this procedure annually places on 

 citrus fruit growers, a careful canvass of the different parties operating 

 tents has been made. This canvass has resulted in showing that 

 approximately 36,000 acres were treated during the year from July, 

 1909, to July, 1910. Many fumigators gave the number of trees 

 which they treated; others the acreage alone. The average orchard 

 will approximate 90 trees to the acre, and in those cases in which 

 estimates were returned in acreage alone, this number has been 

 considered to comprise an acre. Wherever not known, the cost of 

 fumigating a tree has been placed at 30 cents, which price ap- 

 proximates very closely the cost of fumigating the average-sized 

 citrus tree in California. Calculated on this basis, the cost of fumiga- 

 tion of the citrus orchards of southern California during the season 

 1909—1910 approximated $1,000,000. 



THE VARIOUS SYSTEMS OF FUMIGATION. 



Each of the citrus-fruit-producing counties of southern California 

 has a board of horticultural commissioners consisting of three mem- 

 bers whose duties are to supervise the destruction of insect pests, 

 plant diseases, and noxious weeds within their respective counties. 

 In the three greatest citrus-fruit-producing counties — Los Angeles, 

 Riverside, and San Bernardino — numerous inspectors are also 

 employed to assist in carrying on this important work. As a matter 

 of convenience the counties are usually divided into three districts, 

 each of which is supervised by one of the commissioners. If inspectors 

 are employed, usually each is allotted a limited portion of one of 

 these districts, and is held responsible for the proper control of pests 

 therein. He advises when the trees shall be fumigated, and, after 

 arranging for the execution of the work, is supposed to see that it is 

 properly carried out. There are several different systems under 

 which the work may be done. 



BY CONTRACT. 



The larger part of fumigation is carried out under the contract 

 system. Individuals or firms that possess complete equipment for 

 commercial fumigation and practice fumigation as a business, enter 

 into an agreement with the grower, who desires to have his orchard 

 treated, to do the work for a certain sum. The rate is seldom uni- 

 form but varies with such factors as the character of the ground, the 

 acreage, and the size and arrangement of trees. Usually the cyanid 



