Submitted to: American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2000
Publication Date: N/A
Interpretive Summary: The southern root-knot nematode, Meloidogyne incognita, is a major constraint to hot pepper (Capsicum chinense) production. Currently, pre-plant fumigation of soil with methyl bromide and other fumigant nematicides are the primary methods for controlling root-knot nematodes in peppers. However, concern about pesticide use has stimulated interest in the development of alternative pest management strategies with emphasis on development of resistant cultivars. Much of the world's pepper production occurs in hot climates where root-knot nematodes are a severe pest; however, little is known about the stability of root-knot resistance in pepper at high temperatures. The research results reported in this paper demonstrate that root-knot nematode resistance was somewhat reduced at high temperatures (28 and 32C); however, root galling caused by root-knot nematodes was not severe on a resistant pepper cultivar and nematode reproduction was only 60% of that on a susceptible cultivar. Although resistance was somewhat compromised at high soil temperatures, cultivars possessing this resistance should be useful to control M. incognita in temperature, sub-tropical, and tropical areas.
Technical Abstract: Stability of resistance to Meloidogyne incognita was determined in hot pepper (Capsicum chinense and C. annuum) at 24, 28, and 32C. Reactions of the C. annuum cultivars Charleston Belle (resistant to M. incognita) and Keystone Resistant Giant (susceptible) and the C. chinense cultigens PA-426 (resistant) and PA-350 (susceptible) were compared. Root galling and reproduction of M. incognita increased for all genotypes as temperature increased. Severity of galling and nematode reproduction were less (P<0.05) for PA-426 and 'Charleston Belle' compared to PA-350 and 'Keystone Resistant Giant' at all temperatures. However, both PA-426 and 'Charleston Belle' exhibited a partial loss of resistance at the higher temperatures. For example, at 32C, the numbers of M. incognita eggs per gram fresh root for PA-426 and 'Charleston Belle' were in the susceptible range. Nevertheless, the gall index for both cultivars was still within the resistant range. Both PA-350 and Keystone Resistant Giant exhibited highly susceptible reactions at 28 and 32C. Although the resistance of PA-426 and 'Charleston Belle' was somewhat compromised at high temperatures, cultivars possessing this resistance will still be useful for managing M. incognita under high soil temperatures.