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Host-Parasite Relationships in Fall-Sown Sugar Beets Infected by the Stem and Bulb Nematode, Ditylenchus dipsaci

January 2007 , Volume 91 , Number  1
Pages  71 - 79

Pablo Castillo , Institute of Sustainable Agriculture (IAS), Spanish Council for Scientific Research (CSIC), P.O. Box 4084, 14080 Córdoba, Spain ; Nicola Vovlas , Istituto per la Protezione delle Piante, Sezione di Bari, Consiglio Nazionale delle Ricerche (C.N.R), 70126 Bari, Italy ; Andrea Azpilicueta , Newbiotechnic (NBT) S.A., Paseo Bollullos de la Mitación nº 6, Parque Industrial A-49 (PIBO), 41110 Bollullos de la Mitación, Sevilla, Spain ; Blanca B. Landa , College of Agriculture and Forestry (ETSIAM), University of Córdoba (UCO), Edificio C4- “Celestino Mutis”, Carretera de Madrid Km 396, Campus de Rabanales, 14071 Córdoba, Spain, and IAS-CSIC ; and Rafael M. Jiménez-Díaz , ETSIAM-UCO, and IAS-CSIC



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Accepted for publication 28 August 2006.
ABSTRACT

Stunted growth of fall-sown sugar beets (Beta vulgaris) associated with high incidence of crownroot infections and large soil infestations by Ditylenchus dipsaci were observed at the end of the crop growing season in southern Spain by early June 2005. The largest proportion (75%) of the nematode life-stages in plant and soil was the fourth-stage juvenile. The large number (up to 3,750 nematodes per gram of fresh tissue) of D. dipsaci individuals and severe anatomical alterations observed in storage sugar beet roots suggest that the stem and bulb nematode is the causal agent of the impaired growth of sugar beets observed in commercial fields. Observed morphological traits of nematode specimens and results of specific polymerase chain reaction (PCR) and phylogenetic analyses confirmed that the population of D. dipsaci infecting sugar beet belongs to the normal (nongiant) biological type of the nematode. Results of host-range bioassays indicated that the population of D. dipsaci infecting sugar beet in southern Spain reproduces on pea (including seeds and pods), onion, potato, spinach, and tomato, but not on bean, cotton, maize, and tobacco. These results indicate that D. dipsaci may be an important constraint for sugar beet crops in the affected area, but also for other important crops commonly used in rotation with them.


Additional keywords: emerging disease, histopathology, phenotypic and molecular diagnosis

© 2007 The American Phytopathological Society