PRESENT SYSTEM OF SCHEDULING DOSAGE. 23 



THE PRESENT SYSTEM OF SCHEDULING DOSAGE. 



When we understand that up to the present time only one approx- 

 imately accurate dosage schedule has been proposed by the fumiga- 

 tion experts of California, and, what is more confusing, that no two 

 tables agree in all respects, we can not wonder that the practical 

 fumigator has turned from them in perplexity. Finding the tables 

 of little assistance, the fumigator has had to determine his own 

 dosage from practical experience and the results secured. If he 

 failed to destroy the scale on a 6-foot tree in using 1 ounce of cyanid, 

 he increased his dosage for the next 6-foot tree, and so on. He has 

 also learned that the dosage required to destroy some scales is 

 greater than that for other species. Under the system at present 

 in vogue the dosage is usually estimated in the daytime. The 

 estimator, who ordmarily is the man in charge of the outfit, starts 

 out in an orchard equipped with cross-section paper or a schedule 

 sheet. He walks between two rows of trees, jotting down in the 

 corresponding squares of the schedule sheet the dosage which he 

 believes the trees should receive. If he is a careful scheduler he 

 will look at the trees from different sides before indicating the 

 dosage, as trees are sometimes more compact on one side than 

 on another. Less careful men set down the dosage for the two 

 rows of trees while moving along as fast as they can walk. The 

 ^^Titer has seen some schedulers walk through the field at a rapid 

 pace, taking four rows at a time. 



The estimation of dosage in this manner is mainly guesswork. 

 Measurements of the trees are made by the eye; consequently, suc- 

 cessful results depend very largely upon the accuracy of the estimator's 

 eye-measurement, supported by his experience in fumigation. The 

 most careful of estimators are very irregular in their scheduling. 

 This point has already been mentioned by Professor Woodworth.'* 

 From measurements taken after many fumigators, we have found 

 none who did not at times vary more than 50 per cent in dosage esti- 

 mates for trees containing exactly the same cubic contents after being 

 covered with a tent. Frequently the variation is as high as 100 per 

 cent. The results secured by a few of the more careful and expert 

 schedulers have been good as a whole. These men, however, can 

 cover but a small portion of the citi-us groves of southern California 

 in one season. 



The writer has been shown orchards in which it was stated that all 

 the scale had been destroyed by the use of heavy dosages. Even if 

 this were the case it would show that the smallest percentage or 

 strength of dosage used on any tree in those orchards was sufficiently 

 large to destroy the scale. Since, as we have found, expert fumigators 



a Bill. 152, Univ. of CaL Agr. Exp. Sta., 1903. 



