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Title:   Author  item
                                            RUBIO-COVARRUBIAS, OSWALDO - INIFAP. MEXICOitem
                                            Grunwald, Niklaus

                                                         - *Nik*item
                                            CADENA-HINOJOSA, MATEO - INIFAP. MEXICO
  Submitted to: Terra Journal
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 6/1/2005
                                    Publication  Date: 10/1/2005
                                    Citation: Rubio-Covarrubias, O.A., Grunwald, N.J., Cadena-Hinojosa, M.A. 2005. Influence of nitrogen fertilization on incidence of potato late blight in toluca, mexico. Terra Journal. 23:487-493.Interpretive Summary: Nitrogen fertilization and incidence of potato late blight are two important agronomic factors in Mexican potato production. Their relationship was determined in a 3-year study under field conditions in Toluca, Mexico, considered to be the center of origin of the pathogen. The cultivar Alpha, most susceptible to potato late blight, was fertilized with different nitrogen levels varying between 0 and 320 kg N per Ha. The severity of foliar late blight was assessed weekly throughout the growing season. In 1997, final disease severity was less than 10% and no relationship was observed between disease severity and nitrogen fertilization. On the other hand, in 1998 and 1999 final disease severity ranged between 20% and 90%, respectively, and a significant effect of nitrogen fertilization on disease severity was observed. The data from these two years indicate that both deficient and excess nitrogen fertilization can enhance late blight disease. It is thought that nitrogen deficiencies make plants more susceptible, while N excess leads to excessive growth and creates a canopy microclimate conducive to disease development.
                                Technical Abstract: Nitrogen fertilization and incidence of potato late blight are two important agronomic factors in Mexican potato production. Potato late blight is a severe potato disease speculated to be influenced by the amount of nitrogen fertilizer applied to the plant. The relationship between nitrogen fertilization and potato late blight disease was determined in a 3-year study under field conditions in Toluca, Mexico. Toluca is considered to be the center of origin of this pathogen. The cultivar Alpha, most susceptible to potato late blight, was fertilized with different nitrogen levels varying between 0 and 320 kg N per Ha. In 1997, final disease severity was less than 10% and no relationship was observed between disease severity and nitrogen fertilization. On the other hand, in 1998 and 1999 final disease severity ranged between 20% and 90%, respectively, and a significant effect of nitrogen fertilization on disease severity was observed. Our results from these two years indicate that both deficient and excess nitrogen fertilization can enhance late blight disease. It is thought that nitrogen deficiencies make plants more susceptible, while N excess leads to excessive growth and creates a canopy microclimate conducive to disease development.


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