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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #299152
Title: Lack of influence of Meloidogyne incognita on resistance of bell pepper cultivars to Phytophthora capsici

Author
item PARKUNAN, VENKAT - University Of Georgia
item Timper, Patricia - Patty
item JI, PINSHENG - University Of Georgia

Submitted to: Canadian Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2016
Publication Date: 9/5/2016
Citation: Parkunan, V., Timper, P., Ji, P. 2016. Lack of influence of Meloidogyne incognita on resistance of bell pepper cultivars to Phytophthora capsici. Canadian Journal of Plant Pathology. 38(3):375-381. doi:10.1080/07060661.2016.1216012.

Interpretive Summary: The southern root-knot nematode (RKN) and the Phytophthora blight pathogen (Pc) cause root diseases in bell pepper under natural field conditions. However, the interactions between these two pathogens on different bell pepper genotypes are not clear. Greenhouse experiments were conducted on cultivars of bell pepper with different levels of resistance to Pc, Aristotle, Paladin, and Intruder, by concomitant and sequential inoculation of both pathogens. The treatments included inoculating both pathogens simultaneously into the root zone, inoculating RKN 7 days before Pc, inoculating Pc 7 days before RKN, inoculating RKN or Pc alone, and an untreated control without any pathogens. In Aristotle and Intruder, Pc inoculation with RKN simultaneously or 7 days before or after RKN reduced gall index significantly as compared to RKN alone. In Paladin, Pc inoculation 7 days before or after RKN lowered gall index compared to RKN-Pc simultaneous inoculation. Phytophthora blight severity was not influenced by RKN irrespective of inoculation methods used in the three genotypes. In Aristotle, RKN inoculation alone did not reduce fresh root weight, but Pc alone or combined with RKN reduced fresh root weight as compared to the untreated control. However, none of the treatments reduced fresh root weight in Paladin or Intruder as compared to the untreated control. The interaction between Pc and RKN seems to be one way in that Pc reduced galling by RKN, but the nematode had no effect on Phytophthora blight severity. The interaction was influenced by pepper cultivars, with a greater reduction in galling on Aristotle and Intruder than on Paladin.

Technical Abstract: The root-knot nematode, Meloidogyne incognita (Mi), and the Phytophthora blight pathogen, Phytophthora capsici (Pc), cause root diseases in bell pepper under natural field conditions. However, the interactions between these two pathogens on different bell pepper genotypes are not clear. Greenhouse experiments were conducted on cultivars of bell pepper with different levels of resistance to Pc, Aristotle, Paladin, and Intruder, by concomitant and sequential inoculation of both pathogens. The treatments included inoculating both pathogens simultaneously into the root zone, inoculating Mi 7 days before Pc, inoculating Pc 7 days before Mi, inoculating Mi or Pc alone, and a untreated control without any pathogens. In Aristotle and Intruder, Pc inoculation with Mi simultaneously or 7 days before or after Mi reduced gall index significantly as compared to Mi alone. In Paladin, Pc inoculation 7 days before or after Mi lowered gall index compared to Mi-Pc simultaneous inoculation. Phytophthora blight severity was not influenced by Mi irrespective of inoculation methods used in the three genotypes. In Aristotle, Mi inoculation alone did not reduce fresh root weight, but Pc alone or combined with Mi reduced fresh root weight as compared to the untreated control. However, none of the treatments reduced fresh root weight in Paladin or Intruder as compared to the untreated control. The interaction between Pc and Mi seems to be one way in that Pc reduced galling of Mi, but the nematode had no effect on Phytophthora blight severity. The interaction was influenced by pepper cultivars, with a greater reduction in galling on Aristotle and Intruder than on Paladin.