REPORT OF THE SECRETARY 131 



In the spring of 1943 two types of experiments were established, one 

 to test the value of soil poisons in preventing damage by termites; 

 the other to determine whether tropical tree species could be impreg- 

 nated with water-soluble wood preservatives by the sap-stream method 

 of impregnation. Soil poisoning had been previously tested on a 

 small scale particularly in the treatment of soil along building founda- 

 tions to prevent the entrance of termites into wood structure. The 

 relative value of different soil poisons was not known, however, nor 

 was information available on their effectiveness under tropical condi- 

 tions. Thirty-nine different treatments were applied on Barro Colo- 

 rado Island, each treatment being replicated 10 times. The procedure 

 consisted of removing and treating 2 cubic feet of soil, replacing it, 

 and driving a stake into the center of the treated area. After 3 years' 

 exposure it was apparent that treatments by means of the so-called 

 "saw-kerf banding" and bore-hole techniques were the most effective. 

 In the case of several of the tree species, intake of the chemical was 

 not satisfactory and preservation consequently was poor. 



In 1946 the Division, in cooperation with the Corps of Engineers 

 of the War Department, began investigations on problems of de- 

 terioration of wood and wood products confronting the Army. The 

 studies deal mainly with problems under military conditions, and 

 research is pointed towai'd development of practical methods of pre- 

 vention and control which can be readily applied by the Army using 

 materials immediately available on location. Several types of soil- 

 poisoning tests were established on Barro Colorado Island in Novem- 

 ber 1946. An experiment similar to that described above was installed 

 using numerous soil poisons and different dosages. Variations of the 

 method were also tested, one being the surface application of chemi- 

 cals and another the bore-hole method. A soil-poisoning experiment 

 known as the "platform test" was also established. In this test poisons 

 are applied to the soil surface by spraying or sprinkling, and the board 

 or "platform" to be protected is laid on the treated area. Dosages in 

 this test are considerably lighter than in tests described above. The 

 experiment is designed with the object of developing a method of 

 preventing damage to materials in storage dmnps and similar 

 installations. 



The above experiments conducted in cooperation with the War 

 Department comprise a total of approximately 100 treatments; all 

 have been replicated 10 times. 



Experiments on impregnation of seasoned wood with preservatives 

 have been established in order to determine the methods and chemicals 

 most satisfactory for the protection of wood from insect attack. The 

 experiment, like those above, is designed to provide a reasonable 

 degree of preservation by practical methods using chemicals readily 



