EMORY FUMIGATOK FOB GROWING-TREES. 



85 



EMOEY FUMIGATOR FOR GROWING-TREES. 



By Prof. W. G. Johnson, U.S.A. 



In continuation of my last article on the fumigation of nursery stock by 

 hydrocyanic acid gas, I will now describe its application to fruiting trees 

 in- orchards. In California the sheet tent is used almost universally, but 

 in the East I have found a box tent very much more convenient and more 

 easily handled. 



The effectiveness of this gas depends largely upon the accuracy with 

 which the cubic contents of the space is estimated. It is difficult to 

 obtain, with exactness, the cubic contents of a loose tent covering a tree. 

 To overcome this difficulty, I perfected a canvas or box-tent which I call 

 the " Emory Fumigator," as shown in fig. 18. In my first experiments 

 the boxes were constructed on a large scale, so as to cover trees varying 

 from 15 to 20 ft. in height. These boxes were made with hoods which 

 extended from 7 to 10 ft. above the top of the box. They were handled 

 by means of the rigging shown in the figure, which illustrates the 

 equipment in operation in a large Pear orchard. 



It requires three or four men to operate an outfit of this kind, the 

 help depending upon the number of fumigators in use. • It requires one 

 man to look after the chemicals and keep time, while two or three others 



. are necessary in handling the boxes and rigging. The cost of the Emory 

 fumigator depends upon the size. Those shown in fig. 18 are 6 ft. 

 square at base and from 8 to 10 ft. in height, not counting the hood 



i extension. 



These boxes are made of eight-ounce cotton duck, such as used in the 

 Army and Navy for tents and sails. The cloth is tacked over the four 

 sections, the box being fastened together afterwards with screws. The 

 hood is fastened securely around the top and is ready for use. 



When trees are under 8 ft. in height a smaller box can be used to 

 good advantage. A box 5 ft. square at base and 7 to 8 ft. high, with flat 

 top, is perhaps the most useful in orchards for trees of this character. 

 Fig. 19 shows an outfit of this kind in use in the heart of a block of 

 ; 100,000 trees. In this equipment fifteen Emory fumigators were used, 

 and 6,000 Japan Plum trees of various varieties and several hundred 

 Peach trees were fumigated last autumn for about threepence a tree. 



Three strips of ducking, each 20 ft. long, were felled together and 

 securely fastened around a light wooden frame, another piece of cloth 

 was then tucked over the top and around the edges, resulting in a gas- 

 tight enclosure. Boxes of this character cost about ^1 each. At the 

 same time the cloth was not injured. After the duck was removed from 

 the boxes it was used as wagon covers for hauling fruit. Tents or boxes 

 made in this manner are given a heavy coat of boiled linseed oil. This 

 makes them perfectly tight and more durable. 



The chemicals used for the fumigation of orchard trees are the same 

 as for nursery stock, the pi'oportion, however, varying slightly. In the 



