METHODS FOR OBTAINING MEASUEEMENTS AND DOSAGE. 27 



This method might be practicable with a medium-sized tree, 

 but for trees of hirge size, especially seedlings, which are sometimes 

 more than 30 feet in height, its use would doubtless prove difficult, 

 and for field operations multiplication of apparatus should be avoided 

 as far as possible. 



WITHOUT APPARATUS. 



The Woodworth system. — ^The first scheme, so far as the writer's 

 knowledge goes, for obtaining the measurements and dosage of 

 trees without the use of apparatus was suggested by Professor 

 Woodworth.« This method consists of marking on the tent, on two 

 opposite sides and parallel with the edge, a series of lines which are 

 placed at such distances from the center of the tent that they will 

 correspond with differences of 1 ounce in the dosage of trees of the 

 average shape. Upon each of these lines are marked three num- 

 bers; the first indicating the dose (in ounces), the second the cir- 

 cumference on which the dose is based, and the third the amount 

 the dose must be varied when the actual measured circumference 

 is greater or less than that marked on the tent. For trees having a 

 circumference greater than the average between the second figure 

 on the line that is nearest the ground on one side of the tent and 

 the second figure on the corresponding line on the opposite side, 

 the average dose is increased for each additional yard of circum- 

 ference by the amount (in ounces) given by the third figure on the 

 line; for trees having smaller circumferences the figures are corre- 

 spondingly decreased. 



Although the system is fairly accurate, its adaptability for use 

 under the present condition of fumigation in southern California is 

 somewhat questionable. The amount of calculation required to 

 ascertain the dosage for each tree gives large chance of error and is 

 wasteful of time. The possibility of error is still further increased 

 through the necessity of varying the dosage for different species of 

 scale-insects. 



TJie Morrill system.'' — Dr. A. W. Morrill, in the course of his 

 work against the white fly (Aleyrodes citri R. & H.) in Florida, has 

 devised a method of marking tents which is easily the most practi- 

 cable yet proposed for obtaining the distance over the top of a tented 

 tree. Although apparently a modification of the idea presented in 

 the Woodworth method, it is really quite different. In the Wood- 

 worth system the actual dosage is calculated from the figures on 

 the tent. The Morrill system is merely a rapid and simple way of 

 obtaining the distance over the top of a tented tree. 



a Bui. 152, TJniv. of Cal. Agr. Exp. Sta., 1903. 

 &Bul, 76, Bur. Ent. U. S. Dept. Agr., 1908. 



