The southern root-knot nematode, Meloidogyne incognita (Chitwood) Kofoid and White, causes severe yield losses to pepper production in sub-tropical climates throughout the world (DiVito et al., 1985, 1992; Sasser and Freckman, 1987). In the United States, pepper ranks third among crops for use of methyl bromide for preplant fumigation of planting beds to control root-knot nematodes, soilborne diseases, and weeds (U.S. Department of Agriculture, 1998). In accordance with the Montreal Protocol and the U.S. Clean Air Act, methyl bromide has been phased out effective 1 Jan. 2005 (Rich and Olson, 2004; U. S. Environmental Protection Agency, 2000); however, under the U.S. nomination for critical use exemption program, growers continue to use specified allocations (U.S. Environmental Protection Agency, 2006). Other nematocides used for controlling root-knot nematodes in vegetable crops are also being lost from the U.S. market because of human health risks and groundwater contamination. Thus, there is significant interest in the development of alternative methods for managing root-knot nematodes in vegetable crops.
‘Charleston Belle’ and ‘Carolina Wonder’ are the only root-knot nematode-resistant bell pepper cultivars available to commercial growers and home gardeners (Fery et al., 1998). Both of these cultivars are homozygous for the dominant N gene that controls resistance to M. incognita, M. arenaria races 1 and 2, and M. javanica (Thies and Fery, 1998, 2000). Although ‘Charleston Belle’ and ‘Carolina Wonder’ exhibited partial loss of resistance when grown at 32 °C for 8 weeks after inoculation with M. incognita, these cultivars had root gall severity indices that were still in the low resistance range, and the number of M. incognita eggs per gram of fresh root was 95% less for ‘Charleston Belle’ than its susceptible parent, ‘Keystone Resistant Giant’ (Thies and Fery, 2002); similarly, the number of M. incognita eggs per gram of fresh root was 80% less for ‘Carolina Wonder’ than its susceptible parent, ‘Yolo Wonder B’ (Thies and Fery, 1998). Bell peppers are a very important crop in sub-tropical areas of the United States, in particular Florida, where root-knot nematodes are a primary pathogen of vegetable crops. The objective of these studies was to evaluate the effectiveness of the N gene in bell pepper in M. incognita-infested fields under Florida conditions.
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