88 FUMIGATION FOR THE CITRUS WHITE FLY. 



He notes on the scratch pad the first reading and paces around the 

 tent, noting on the pad the reading on the opposite end of the selected 

 line. Upon reaching the starting "point the distance over and the 

 circumference — as, for example, 38-44 — are noted at once upon the 

 diagram (fig. 3, D; figs. 4, 5). The dosage table is referred to and the 

 amount of cyanid to be given is noted in the diagram below the figures 

 noting the dimensions. The foreman or the man who determines 

 the amount of chemicals then assists in measuring and introducing 

 the chemicals, or if two other men are available for this work he pro- 

 ceeds to the next tree and determines the dosage as before. 



The suppl}^ of water and chemicals for the set of tents is moved 

 ahead as fast as the generating of the gas is started under each tree. 

 The assistant, when working on the second set of trees, picks up the 

 generating jars beneath the first trees recently fumigated and midway 

 betvv^een the rows scoops out a hole with his foot or with a spade and 

 buries the contents of the jar. The foreman should never trust any 

 responsible part of the operation to an assistant whom he does not 

 know to be reliable. He should thoroughly systematize the work so 

 that no unnecessary hands will be employed while at the same time 

 his entire outfit of tents will be utilized to the best advantage. 



ESTIMATION OF TIME REQUIRED FOR FUMIGATION OF GROVE. 



When two men can conveniently shift the tents, they can cover a 

 tree, take the measurements, and generate the gas without difficulty 

 in about five minutes when not hampered by irregularities in the 

 location of trees. This means that two men should be able to handle 

 9 or 10- tents in forty-five minutes with the methods herein recom- 

 mended. Allowing fifteen minutes each hour for rest and restock- 

 ing of the commissary tray with chemicals, two men beginning 

 at 4 p. m. could fumigate about 75 trees by midnight. Three men 

 in the same time could easily fumigate 100 or 115 trees somewhat 

 larger in size, or at the rate of 13 or 14 tents every hour. Four or five 

 men should be able to fumigate each hour from 20 to 25 trees as large 

 as can conveniently be covered by means of changing poles. When 

 uprights are used a crew of six men, or possibly in some cases as many 

 as. eight, can work to best advantage. Such a crew should handle 

 from 10 to 15 tents 50 feet in diameter, or larger, every hour, including 

 time for rest and restocking cart or tray with the chemicals. 



With three men attending to determining the dosage and generating 

 the gas and two men shifting the tents, the trees being 12 to 15 feet 

 high, the author with other agents of the Bureau in experimental 

 work on one occasion fumigated 19 trees in thirty -five minutes. In 

 one night a crew of six men have fumigated 221 budded trees varying 

 from 12 to 16 feet in height. In this case certain irregularities in 

 the plan of setting the grove prevented a much better record. 



