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Phytophthora Foot Rot of Black Pepper in Brazil and Puerto Rico. R. Alconero, Research Plant Pathologist, the Federal Experiment Station, Plant Research Division, ARS, USDA, Mayaguez, Puerto Rico 00708; F. Albuquerque(2), N. Almeyda(3), and Alma G. Santiago(4). (2)Plant Pathologist, Instituto de Pesquisas e Experimentacao Agropequarias do Norte, Belém, Pará, Brazil, and Chief of Research of Conselho Nacional de Pesquisas; (3)(4)Agricultural Research Technician, and Biological Laboratory Technician, respectively, the Federal Experiment Station, Plant Research Division, ARS, USDA, Mayaguez, Puerto Rico 00708. Phytopathology 62:144-148. Accepted for publication 13 August 1971. DOI: 10.1094/Phyto-62-144.

Foot rot epidemics of black pepper (Piper nigrum) caused by Phytophthora palmivora are usually observed when plants are of bearing age (2 or more years old). Younger plants also are susceptible, and may collapse rapidly if inoculum concentrations are high. In areas new to black pepper cultivation, the amount of inoculum in the soil probably is low. Consequently, development of root infections into severe foot rots at the soil line occurs slowly. An increase in number and mobility of infective zoospores results in increased infection, rapid deterioration of roots, and collapse of the infected plants. Several commercial varieties are equally susceptible. Grafts on disease-resistant Piper colubrinum deteriorate after the 4th year.