Incidence of potato tuber blight in Ecuador


Potato late blight, caused byPhytophthora infestans (Mont.) de Bary, is the most important biotic constraint to potato yield and productivity in Ecuador. Yields are severely reduced by foliage blight, but tuber blight has never been quantified in this country. To address this issue, three independent surveys were carried out in Ecuador to estimate the incidence of tuber infection byP. infestans. The first two (1998–1999) involved the collection and assessment of more than 8,000 tubers from the four provinces that produce the most potatoes: Carchi, Chimborazo, Pichincha, and Tungurahua. In the third survey (1999–2001), approximately 10,000 tubers were sampled from the two provinces producing the most potatoes, Carchi and Chimborazo, and from Canar and Bolivar, two provinces that produce relatively small amounts. In spite of confirmed foliage infection in most fields sampled, very few infected tubers were found. In 1999, an extremely low incidence of tuber blight (less than 0.1%) was detected in three samples (each of more than 1,000 tubers) from the province of Pichincha. In a separate survey in 1999, tuber blight was also found in three fields in the province of Carchi, but with very low incidence. Our data indicate that tuber blight does occur in Ecuador, but the incidence of the disease is extremely low. Factors that might suppress tuber blight in Ecuador are discussed.


El tizón tardío de la papa causado porPhytophthora irtfestans (Mont.) de Bary, es el problema biótico de mayor importancia para el rendimiento y productividad de la papa en Ecuador. Los rendimientos se reducen severamente por los daños en las hojas, pero nunca se ha determinado el daño que produce en los tubérculos. Se hau hecho encuestas en Ecuador, con el fin de determinar la incidencia de la infección deP. infestans en los tubérculos. Las primeras dos (1998 y 1999) incluyeron la colección y evaluación de más de 8,000 tubérculos provenientes de las cuatro provincias donde se produce la mayor cantidad de papa: Carchi, Chimborazo, Pichincha y Tungurahua. En la tercera encuesta (1999–2000) se revisaron aproximadamente 10,000 tubérculos de las provincias de mayor producción Carchi y Chimborazo y de las provincias de Canar y Bolivar que producen relativamente poca cantidad. A pesar de que se confirmó infección en la mayoría de los campos revisados, se encontraron muy pocos tubérculos infectados. En 1999, año de muy poca incidencia de dano al tubérculo (menos del 0.1% ) se encontre en tres muestras (de mas de 1,000 tubérculos por muestra) de la provincia de Pichincha. En una encuesta aparte en 1999, se encontraron danos al tubérculo, aunque en baja incidencia, en tres campos de la provincia de Carchi. Nuestros datos indican que si bien existen daños al tubérculo, la incidencia es extremadamente baja. Se discuten los factores que podrían suprimir el daño al tubérculo en Ecuador.

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Correspondence to Pedro J. Oyarzún or Gregory A. Forbes.

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Oyarzún, P.J., Garzón, C.D., Leon, D. et al. Incidence of potato tuber blight in Ecuador. Am. J. Pot Res 82, 117–122 (2005).

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Additional Key Words

  • Andisols
  • high organic matter
  • traditional agriculture