Explanation:

Cultivation of rubber in Brazil, its native  habitat,  was  severely hindered by blight in the early 20th century. At present, most of the world’s natural rubber is produced by rubber trees descended from rubber seedlings transplanted from South America to south and south east Asia. The most severe disease is South American Leaf Blight (SALB). This disease is endemic throughout the rubber growing areas in the Americas. It also poses a major global threat.  The  fungus can be controlled by a number of fungicides. Some species are not susceptible to the disease,  and  some  strains of susceptible species are resistant. Crown budding  or grafting of resistant plants onto productive trees can be used to control spread.