ILLUSTRATIONS. 



PLATES. 



Page. 



Plate I. Method of covering small tree with bell or hoop tent 16 



II. Fig. 1.— Brick furnace, tank, and derrick used in the tannin treat- 

 ment for mildew, San Bernardino County, Cal. Fig. 2. — Machine 

 for covering trees with sheet tents 20 



III. Fig. 1. — Method of attaching tent to hoisting pole by a half hitch of 



the rope. Fig. 2. — Top of derrick, showing method of attaching 

 pulley. Fig. 3. — Base of derrick, showing method of construct- 

 ing braces 22 



IV. Fig. 1. — Supply cart used with the improved system of fumigation. 



Fig. 2. — Supply wagon devised by C. E. McFadden, of Fullerton, 



Cal 22 



V. Figs. 1-5. — Successive stages in placing a tent over a tree with 

 poles. Fig. 6. — A tented tree, showing method of securing the 

 distance around the bottom of the tent by means of a tape at- 

 tached to an iron rod 26 



VT. Removing the tent from one tree onto another by means of poles. . 26 



VII. Placing a sheet tent over a tree by means of derricks 28 



VIII. Fig. 1. — A row of tented trees, with cart at one end of row, ready to 



commence dosing. Fig. 2. — Dosing a tree 38 



IX. Dosage Schedule A. for high-grade sodium cyanid 88 



X. Dosage Schedule f-A. for high-grade sodium cyanid 88 



TEXT FIGURES. 



Fig. 1. Map showing principal localities in southern California where citrus 



fruits are produced 7 



2. Plan for construction of octagonal sheet tent, 50 feet across, showing 



lines used in constructing octagon 14 



3. Method of attaching hooks to tent when covering trees with aid of der- 



ricks 16 



4. Ends of hoisting poles used in placing tents over trees 20 



5. Earthenware acid jar with attachments for field use. 23 



6. Carboy with handles attached to facilitate pouring the acid and carrying 



the carboy 26 



7. Outline of a sheet fumigation tent marked according to the Morrill 



method 29 



8. Man carrying tray and water bucket as practiced under the old system 



of fumigation 31 



9. Dosage schedule Xo. 1, for potassium cyanid 34 



10. Chart showing total amount of gas evolved when different proportions 



of water are used 45 



11 . Dosage schedule No. f , for potassium cyanid 59 



12. A cover device attached to a fumigation generator 75 



13. Laboratory apparatus used in the decomposition of cyanids and collec- 



tion of the liberated hydrocyanic-acid gas 100 



IX 



