CHAPTER IX 

 ESTIMATING GAS FOR ORCHARD WORK 



A 



MOUNTS OF CHEMICALS. The foreman or super- 

 intendent should be responsible for the chem- 

 icals used for making the gas. As a rule, 

 where the sheet tents are used, different 

 amounts are necessary for individual trees, espe- 

 cially where they vary in size. The superintendent 

 judges the size of the tree as soon as it is tented, 

 and estimates and weighs the chemicals accord- 

 ingly. It is difficult to estimate the cubic contents 

 of a tented tree, and as a result some unsatisfac- 

 tory work is done. Indeed, it is surprising that the 

 results are as uniform as they are. In California the 

 trees to be fumigated are usually inspected in advance, 

 so that the superintendent can, in a general way, esti- 

 mate the amount of gas necessary. A little more gas 

 than the tree will stand without injury is usually pro- 

 duced. This is somewhat misleading, for the larger 

 the tree the greater the injury. If the dose is properly 

 proportional to the cubic content, there is a slower 

 diffusion of the gas, in which case care must be taken 

 when large trees are fumigated. 



The usual method is to measure the tree and find 

 the amount of chemicals necessary -by reference to a 

 table prepared for that purpose. If the tables are cor- 

 rectly calculated and the measurement accurately done 

 this is perhaps the safest method. As already indi- 

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