20 T O R R E Y A 



Indies. There followed an amazing development of the rubber plantations in 

 the East, paralleled by the nearly complete abandonment of the rubber pro- 

 duction industry in the Western Hemisphere. 



The latent danger in the complete dependence of the United States on 

 eastern rubber supplies gave rise to governmental action in 1940 when a bill 

 was passed by Congress authorizing expenditure of a half million dollars for 

 investigations directed toward the development of rubber production in the 

 Western Hemisphere. The Bureau of Plant Industry was charged with the 

 conduct, in cooperation with other agencies, of these investigations. 



The first step was a survey of the Western Hemisphere areas falling 

 within the range to which Hevea is adapted, or in other words between the 

 equator and about 20° of latitude. Simultaneously plans were laid for the 

 development of rubber plantings within suitable areas. The general plan 

 is for the development of small one-man or one-family plantations in regions 

 having the proper soil and being otherwise climatically and economically 

 adapted. It is thought that small-farm rubber cultivation has a far greater 

 chance of success in the Western Hemisphere than would large plantation 

 enterprises, although an interspersion of large and small units is probably 

 most desirable. 



The most serious problem relating to the cultivation of Hevea in Latin 

 America is the widespread presence of the South American leaf blight, caused 

 by Dothidella ulei. This disease is spread through the whole native range of 

 Hevea in the Amazon Valley and its further spread to other Latin American 

 areas where Hevea can be grown successfully is quite likely. It has been the 

 cause of the abandonment of numerous former attempts to establish rubber 

 plantations in the west. However, in the last ten years or so several disease 

 resistant clones have been developed, mostly in the plantings of the Ford 

 Motor Company begun in 1927 in Brazil, and in those of the Goodyear Tire 

 and Rubber Company begun in 1935 in Panama, and in 1936 in Costa Rica. 

 Further selection of resistant strains for building of clones is one of the goals 

 of the present cooperative program. A discussion of the disease problems and 

 the methods used for overcoming them is given by Rands (1942) in an article 

 regarding the various aspects of Hevea culture in Latin America. 



The other aim of the selection and breeding work under way is the 

 development of high-yielding strains. Many of the eastern clones of Hevea 

 selected and bred during the last few years have exceedingly high rubber 

 yields. The combination of these high rubber yields with high leaf blight 

 resistance is counted upon to provide superior strains for the new western 

 plantings. 



Gastilla elastica deserves mention in any roster of the rubber bearing 

 plants, not because it plays any appreciable part at present in the cultivation 



