FUMIGATION OF CITRUS TREES. 19 



In places like Florida, as well as in tropical countries where tents 

 become wet every night, treatment to prevent mildew would seem 

 advisable. Even in California it will act as a guarantee to those 

 fumigators who exercise little care in the drying of their outfit. 

 The dipping and boiling of tents in a solution of tannin is the only 

 method now practiced there to render them proof against mildew. 

 This tannin treatment has been in use for a long time, and is very 

 satisfactory. Contrary to the belief of many, tannin does not render 

 the tents any tighter. It merely shrinks them, winch can be as well 

 accomplished by dipping in water, or a few nights' exposure to heavy 

 dews will produce the same results. The tannin treatment, as prac- 

 ticed by Mr. S. A. Pease, horticultural commissioner of San Bernar- 

 dino County, is as follows: 



A brick furnace [Plate II, fig. 1] is constructed so that the upper half partially 

 incloses a tank, 3 by 10 feet and 3 feet deep, made of Xo. 16 galvanized iron. This is 

 filled with water to within 8 inches of the top, which would be about 500 gallons, and 

 about 200 pounds of extract of oak bark is added. This mixture is raised to a tem- 

 perature as high as the hands of the operators will stand. A tent stretched out in as 

 loosened a condition as possible (not in a wad) is then introduced into the vat. It is 

 stirred around and kept submerged by means of wooden paddles manipulated by the 

 crew. After 20 or 30 minutes of this treatment the tent is raised to the top of a derrick 

 above the tank and suspended for a few minutes until well drained, after which it is 

 lowered on a rack, moved away, and spread out on the ground to dry. Twenty-five 

 gallons of water and 20 pounds of extract are now added to the tank before another 

 tent is introduced, and this is repeated for each succeeding one. 



The above recommendations are for 45-foot tents. Larger tents 

 require more material and smaller ones less. Oak-bark extract costs 

 about 10 cents per pound by the barrel. 



MARKING. 



On pages 29-30 of this bulletin is explained a method of marking 

 tents, which is used in the most improved fumigation procedure. 

 Tents should have been thoroughly wet at least once before being 

 marked, as new cloth is subject to considerable shrinkage, and if 

 marked before shrinkage the measurements will be erroneous. Meas- 

 urements made of several tents of 6|-ounce drill, before and after 

 shrinkage, showed that 45-foot covers shrink about 3 feet length- 

 wise of the strips of cloth. The crosswise shrinkage is much less. A 

 convenient method of shrinking untreated tents is to spread them 

 out on the lawn and wet with a hose or sprinkler. After being dried 

 they are ready for marking. Tents treated with tannin should be 

 marked after the treatment. 



The best method for marking tents is to place them on a smooth 

 floor. If this is not possible, spread them out on the smoothest 

 ground available. A tapeline, brush, and marking fluid are required. 

 Printer's ink, diluted, is the best marking material, although some 



