FUMIGATION OF CITRUS TREES. 35 



determined they were introduced into a chart of the same general 

 form as that used by Dr. Morrill. Such a chart form has been known 

 in scientific work for many years and was first introduced into fumi- 

 gation scheduling by Prof. Woodworth. 1 



An average-sized orange tree, one 41 feet in circumference by 28 

 feet over, was taken as a basis in the preparation of the schedule. 

 The cubic contents of the tree was determined and a dosage calcu- 

 lated which would give it 1 ounce to each 100 cubic feet. Trees of 

 other dimensions, both larger and smaller, were then considered and 

 their contents determined. In working out the dosage for these other 

 trees not only was the cubic contents taken into consideration but 

 also the rate of leakage as compared with that of the tree 41 by 28 

 feet in size. Trees winch were smaller than tins would have a greater 

 proportional leakage rate while the larger ones would have less, as ex- 

 plained on pages 33-34. In securing the dosage for various trees, those 

 smaller than 41 by 28 were given sufficient cyanid in excess of 1 ounce 

 per 100 cubic feet to offset the increased leakage, while the dosages for 

 larger trees were proportionately decreased below the 1 -ounce rate. 

 This allowance for leakage so modified the schedule that some of the 

 smaller trees were receiving in excess of 1J ounces per 100 cubic feet, 

 while trees as large as 60 by 44 were receiving only about three-fourths 

 of an ounce to the same space. It thus can be seen that each dosage 

 was worked out independently and so correlated to the other dosages 

 that when placed in schedule No. 1 the ultimate result was that of a 

 schedule which should approximate uniform results throughout. 



How to use the chart. — Referring again to figure 9, the top line of 

 numbers, commencing at 16 and continuing up to 68, represents the 

 distance, in feet, around the bottom of the tent. The outer vertical 

 columns of numbers, on either side, commencing at 10 and increasing 

 regularly to 49, represent the distance, in feet, over the top of the tent. 

 The dosage of a tree of known dimensions is found in that square where 

 the vertical column headed by the distance around the tree intersects 

 the horizontal line of figures corresponding to the distance over. For 

 instance, in the case of a tree 40 feet around by 28 feet over, in the top 

 line of numbers 40 is next after the third heavy vertical line. The 

 dosages computed for trees 40 feet around are to be found in the ver- 

 tical column headed by this number, which commences with 7 and 

 ends with 16. Then the vertical column of large figures at either 

 margin is followed down until 28 is reached. All dosages computed 

 for trees 28 feet over are found in this horizontal line of figures, which 

 commences with 8 and ends at 16. The dosage for a tree 40 by 

 28 feet is found at the intersection of this line with the vertical col- 

 umn headed with 40, that number being 11, the required dosage of 

 cyanid in ounces. Before the numbers 20, 30, 40, and 45 in the lines 



1 Bui. 152, Univ. of Cal. Agr. Exp. Sta., p. 6, 1903. 



