Puerto Rican mycologist, Chardón was not only the first native Puerto Rican to study fungi but also highly influential in the study of the diseases of crop plants. He became involved in agricultural development and went on to advise the governments of a number of Antillean and Latin American countries on economic issues.
Born in Ponce, he attended the College of Agriculture and Mechanical Arts (Mayagüez) until it was tragically destroyed in an earthquake in 1918 when he moved to Cornell University in New York. Here he completed his bachelor's degree and continued to study for a master's in the diseases of sugar cane under the direction of Professor H.H. Whetzel, who was an important influence in Chardón's decision to study mycology and phytopathology.
On his return to Puerto Rico in 1921 he began to work studying plant diseases. Appointed as a phytopathologist at the Agricultural Experimental Station in Río Piedras, it was here that he made one of his most important contributions to the field when he discovered the aphid vector of sugar cane mosaic virus in 1922.
Between 1923 and 1930 Cardón worked for the Puerto Rican government as Commissioner of Agriculture and Labour, studying the diseases of sugar cane and tobacco. During this time he made many trips to Colombia, reorganising the School of Agriculture in Medellín in 1926 and taking charge of the Agriculture Mission of Valle de Cauca in 1929 when he established an Experimental Station in Palmira.
In 1931 he was appointed Chancellor of the University of Puerto Rico, the first native to have been given this position. Later he became directly involved in the economic development of his country, organising the Puerto Rico Reconstruction Administration (PRRA) in which he encouraged the training of agricultural technicians, known as the Plan Chardón.
Chardón was a man of strong integrity and conviction; he defended the truth and was not willing to give up his beliefs. This began to interfere with his work for the Puerto Rican government, with which he had major disagreements, and he soon resigned from the PRRA and the University. In 1936 he decided to leave the country, moving to Colombia to continue his agricultural work with their government. For the rest of his life Chardón continued his studies and was invited to conduct surveys in many Latin American countries, travelling to the Andes of Venezuela and Colombia to collect plants and fungi. He also developed economic plans for a number of countries, notably the Dominican Republic in 1937 and Iran. He would later return to work for Puerto Rican organisations, as director of both the Land Authority (1940) and the Tropical Agricultural Institute in Mayagüiz (1943-1946).
His studies in the field of mycological taxonomy focused around the family Pyrenomycetes, in which he discovered several new species and genera, and publishing two books entitled Mycological Explorations of Colombia (1930) and Venezuela (1934). One species he discovered, the Oomycete Albugo chardoni W. Weston, is named after him.
Chardón also aided N.L. Britton in the creation of the 14 volume Scientific Survey of Puerto Rico and the Virgin Islands, and wrote two books on exploration, both his own and that of other naturalists: Viajes y Naturaleza and Los Naturalistas en América Latina, the latter remained unfinished and only one volume was published when he died in San Juan aged 68. Chardón was awarded two honorary doctorates, one from Dartmouth College in New Hampshire (1935) and the other from the University of Puerto Rico in Río Piedras (1953). He was also awarded the Liberators Cross and the Medal of Honour in Public Instruction by the Venezuelan government for the contributions he made in science there.
