Puerto Rican Mosaic Infection

Date: 1921
Owner: Journal of Agriculture of Porto Rico
Source Type: Images


This map of Puerto Rico illustrates the regions of the island most affected by the mosaic disease, a virus that began ravaging Puerto Rico's sugarcane industry in 1917. As the map makes clear, Puerto Rico was dominated by monocrop agriculture, namely of coffee, tobacco, and sugar (the sugar growing areas being located mostly along the coast), and its economy relied almost exclusively on their production. The necessity of protecting the cane fields from this virus attracted the attention of scientists from the United States and Puerto Rico.

The virus was a new concept in biology at this time, and scientists had difficulty pinpointing the nature of the mosaic disease as well as how it was passed from plant to plant. The U.S.D.A. sent cane specialists in an effort to protect their considerable interests in Puerto Rico and they were able to determine that the mosaic was a virus spread by an external vector (just as Cuban doctor Carlos Juan Finlay had realized that yellow fever was spread by mosquitoes). It was two Puerto Rican scientists, Carlos E. Charon and Rafael A. Veve, who figured out that the disease was spread by the corn aphid, an insect that did not normally eat cane but did so after weeds (their usual fare) were removed from the fields. As historian Stuart McCook notes, the mosaic virus is a prime example of the role humans can play in changing nature on a global scale. The virus came to Puerto Rico from the Pacific islands as planters sought to import new strains of cane. The mosaic disease still would not have thrived in the Caribbean's natural conditions, but weeding the cane fields made an artificial environment in which aphids were forced to eat (and thus infect) sugarcane.


McCook, Stuart George. States of Nature: Science, Agriculture, and Environment in the Spanish Caribbean, 1760-1940. Austin: University of Texas Press, 2002. 

CITATION: Journal of Agriculture of Porto Rico, 1927