Location: Vegetable Research
Title: Does infection by southern root-knot nematode influence development of Phytophthora blight in pepper? Authors
Submitted to: International Phytophthora Capsici Conference
Publication Type: Proceedings
Publication Acceptance Date: November 15, 2012
Publication Date: N/A
Technical Abstract: The southern root-knot nematode, Meloidogyne incognita, and Phytophthora capsici, the causal agent of Phytophthora blight, are both important pathogens of pepper (Capsicum annuum L.) in the U.S. and worldwide. Although there is significant information in the literature about the responses of pepper to independent infection by P. capsici or M. incognita, information is lacking about whether infection by M. incognita influences development of Phytophthora blight in pepper. In greenhouse tests, we studied the responses of five pepper genotypes to inoculation with one or both pathogens. Each of the pepper genotype x pathogen treatments also were subjected to treatments with a fungicide (mandipropamid) and/or a nematicide (oxamyl); a non-treated control was also included for each pepper genotype. The pepper genotypes were CM-334, a serrano-type pepper (resistant to M. incognita and P. capsici), and 4 bell peppers: Charleston Belle (M. incognita resistant); R4 (moderately high resistance to P. capsici); Aristotle (moderately resistant to P. capsici); and Jupiter (susceptible to P. capsici). Response to M. incognita: CM-334 and Charleston Belle exhibited high resistance to M. incognita (percentage of root galling = 0% and 1%, respectively). Jupiter, Aristotle, and R4 were susceptible to M. incognita (percentage of root galling ranged from 45% to 68%). Oxamyl treatment was effective in controlling M. incognita in the root-knot susceptible bell pepper genotypes (percentage of root galling ranged from 0% to 2%). Response to P. capsici: CM-334 was resistant to P. capsici with 7% root necrosis and 12% crown necrosis. All of the bell peppers were susceptible to P. capsici (root necrosis ranged from 30% to 33% and crown necrosis ranged from 50% to 65%). Bell peppers treated with mandipropamid had less (P = 0.0165) crown necrosis than non-treated plants (23% vs. 58%). Response to co-inoculation with M. incognita and P. capsici: In these studies, the development of Phytophthora blight was not significantly different in plants that were inoculated with P. capsici alone or with both P. capsici and M. incognita. This information suggests that resistance to Phythophthora blight in pepper cultivars which lack resistance to root-knot nematodes would not be compromised by M. incognita infection.