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Inoculum Density-Disease Development Relationship in Verticillium Wilt of Artichoke Caused by Verticillium dahliae

September 2007 , Volume 91 , Number  9
Pages  1,131 - 1,136

M. Berbegal , Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain ; A. Ortega , Universidad Miguel Hernández, Escuela Politécnica Superior de Orihuela, Dpto. de Producción Vegetal y Microbiología, Ctra. Beniel km 3.2, 03312 Orihuela, Alicante, Spain ; and J. García-Jiménez and J. Armengol , Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Spain



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Accepted for publication 2 April 2007.
ABSTRACT

The relationship between inoculum density of Verticillium dahliae in soil and disease development was studied in 10 commercial artichoke fields. Inoculum density of V. dahliae varied between 2.2 and 34.2 microsclerotia (ms) g--1 of soil near planting. Artichoke plants were monitored for disease at the beginning and the end of each growing season. There was a significant correlation, which was best described by negative exponential models, between inoculum density and disease incidence, symptom severity, and recovery of the pathogen from the plants. Inoculum densities ranging from 5 to 9 ms g--1 of soil were associated with a mean percentage of infected plants of about 50%. Additionally, three fields were monitored in two consecutive growing seasons to evaluate the population dynamics of V. dahliae microsclerotia in soil and disease development. Numbers of microsclerotia per gram of soil decreased significantly by the end of the first growing season but slightly increased at the end of the second growing season. In these fields, symptom severity was greatest during the second growing season when high percentages of infected plants also were recorded.


Additional keywords: Cynara cardunculus L. var. scolymus

© 2007 The American Phytopathological Society