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Richard L. Fery and Judy A. Thies

Scotch Bonnet and Habanero peppers, extremely pungent cultivar classes of Capsicum chinense Jacq., are increasing in popularity in the United States. Because the southern root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood, is a major pest of many C. annuum cultivars, a series of greenhouse and field experiments was conducted to determine if Scotch Bonnet and Habanero peppers from available commercial and private sources also are vulnerable to the pest. In an initial greenhouse test, a collection of 59 C. chinense cultigens was evaluated for reaction to M. incognita race 3. All cultigens obtained from commercial sources were moderately susceptible or susceptible. However, four accessions obtained through Seed Savers Exchange listings exhibited high levels of resistance. Three of these cultigens (PA-353, PA-398, and PA-426) were studied in subsequent greenhouse and field plantings, and each was confirmed to have a level of resistance similar to that available in C. annuum. All three of the resistant cultigens are well-adapted and each is potentially useful in commercial production without further development. None of the Habanero cultigens was resistant to the southern root-knot nematode. The resistant Scotch Bonnet cultigens may serve as sources of resistance for development of root-knot nematode—resistant Habanero peppers.

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Janice R. Bohac, D.M. Jackson, John D. Mueller, and P.D. Dukes Sr.

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Jorge Pinochet

‘Greenpac’ is a new peach hybrid rootstock [Prunus persica (L.) Batsch × P. davidiana (L.) Batsch] × [P. dulcis (Mill.) D.A.Webb × P. persica] developed by Agromillora Iberia, S.L., Barcelona, Spain, for use mainly as a rootstock for peach and nectarine cultivars but can also be used for almond. Trees are green leaf with a vigor comparable to that of ‘GF 677’ or ‘Garnem’ (Felipe, 2009). Plants propagate well by in vitro and exhibit a uniform growth in the nursery that allows early budding. ‘Greenpac’ is root knot nematode-resistant to

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Judy A. Thies and Amnon Levi

Root-knot nematodes [Meloidogyne arenaria (Neal) Chitwood, Meloidogyne incognita (Kofoid & White) Chitwood, and Meloidogyne javanica (Treub) Chitwood] are serious pests of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] in the southern United States and worldwide. Watermelon cultivars with resistance to any of these nematode pests are not available. Therefore, we evaluated all accessions of Citrullus colocynthis (L.) Schrad.(21) and Citrullus lanatus (Thunb.) Matsum. & Nakai var. citroides (L.H. Bailey) Mansf.(88), and about 10% of C. lanatus var. lanatus (156) accessions from the U.S. Plant Introduction (PI) Citrullus germplasm collection for resistance to M. arenaria race 1 in greenhouse tests. Only one C. lanatus var. lanatus accession exhibited very low resistance [root gall index (GI) = 4.9] and 155 C. lanatus var. lanatus accessions were susceptible (GI ranged from 5.0 to 9.0, where 1 = no galls and 9 = ≥81% root system covered with galls). All C. colocynthis accessions were highly susceptible (GI range = 8.5 to 9.0). However, 20 of 88 C. lanatus var. citroides accessions were moderately resistant with a GI range of 3.1 to 4.0; overall GI range for the C. lanatus var. citroides accessions was 3.1 to 9.0. Resistance to M. arenaria race 1 identified in the C. lanatus var. citroides accessions was confirmed on a subset of accessions in a replicated greenhouse test. The results of our evaluations demonstrated that there is significant genetic variability within the U.S. PI Citrullus germplasm collection for resistance to M. arenaria race 1 and also identified C. lanatus var. citroides accessions as potential sources of resistance.

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Richard L. Fery and Philip D. Dukes

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R. L. Fery, P. D. Dukes, and W. L. Ogle

Abstract

‘Carolina Cayenne’ pepper (Capsicum annuum L.) has been released by the USDA and Clemson Univ. as a replacement for ‘Carolina Hot’, a widely adapted home garden and commercial cultivar that was released by Clemson Univ. in 1954 (2). The major attribute of the new cultivar is its exceptionally high level of resistance to southern root knot, a major root disease of pepper caused by the nematode Meloidogyne incognita (Kofoid & White) Chitwood. ‘Carolina Hot’ exhibits a variable reaction to M. incognita, and results of field trials indicate that this parasite can reduce the marketable fruit yield of susceptible ‘Carolina Hot’ plants by as much as 87.5% (1).

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Dale E. Kester and R. N. Asay

Abstract

Two new, patented, vegetatively propagated Prunus rootstocks are being released for commercial use. These rootstocks are hybrids of an almond selection, Almond B, crossed with Peach Selection 1-8-2 by the late Carl J. Hansen. These rootstocks are being released primarily for use with almond but also can be used as rootstocks for peach, plum, and prune.

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Judy A. Thies and Richard L. Fery

Several species of root-knot nematodes [Meloidogyne incognita (Kofoid & White) Chitwood, M. arenaria (Neal) Chitwood, M. javanica (Treub) Chitwood, and M. hapla Chitwood] are major pests of peppers (Capsicum spp.) in the United States and worldwide. Resistance to M. incognita, M. arenaria, and M. javanica has been identified in several Capsicum accessions, but there are few reports of resistance to M. hapla. Therefore, we selected a 10% core (440 accessions) of the 14 available Capsicum spp. in the Capsicum germplasm collection (3,731 accessions) maintained by the U.S. Dept. of Agriculture (USDA), and evaluated this core for resistance to M. hapla in unreplicated greenhouse tests. The 11 best (most resistant) and the 3 worst (most susceptible) accessions identified in these unreplicated tests were re-evaluated in a replicated greenhouse test. Seven of these 11 “best” accessions (PI 357613, PI 357503, PI 439381, PI 297493, PI 430490, PI 267729, and PI 441676) exhibited root gall severity indices <5.0 (1 = no galls; 9 = more than 80% of the root system covered with galls) in the replicated test, and each of these indices was significantly lower than the indices of the “worst” accessions and susceptible controls. Although a gall index <5.0 indicates a moderate level of resistance, more than 3000 M. hapla eggs were extracted per gram of fresh root tissue and the reproductive index was >1.0 for each of these accessions. These observations suggest that the most resistant accessions tested are somewhat susceptible to M. hapla. The results of our evaluation of a core of the USDA Capsicum germplasm collection demonstrates clearly that there is significant genetic variability within the overall collection for M. hapla resistance. Additionally, these results identify portions of the collection where future evaluations for M. hapla resistance should be focused. For example, the origin of the two most promising C. annuum accessions (PI 357613 and PI 357503) in the core was Yugoslavia. Thus, additional accessions from this temperate region of the world should receive priority attention in any effort to identify better sources of resistance in C. annuum to M. hapla.

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Judy A. Thies, Richard F. Davis, John D. Mueller, Richard L. Fery, David B. Langston, and Gilbert Miller

Root-knot nematode-resistant `Charleston Belle' bell pepper (Capsicum annuum L. var. annuum) and metam sodium treatment were evaluated for managing the southern root-knot nematode [Meloidogyne incognita (Chitwood) Kofoid and White] in fall-cropped cucumber (Cucumis sativus L.). `Charleston Belle' and its susceptible recurrent parent, `Keystone Resistant Giant', were planted as spring crops at Blackville, S.C., and Tifton, Ga. `Charleston Belle' exhibited high resistance and `Keystone Resistant Giant' was susceptible at both locations. After termination of the bell pepper crop, one-half of the plots were treated with metam sodium delivered through the drip irrigation system. Cucumber yields and numbers of fruit were highest for cucumber grown in plots treated with metam sodium following either `Charleston Belle' or `Keystone Resistant Giant'; however, root gall severity and numbers of M. incognita eggs in the roots were lowest for cucumber grown in plots treated with metam sodium following `Charleston Belle'. Conversely, root gall severity and nematode reproduction were highest for cucumber grown in plots following `Keystone Resistant Giant' without metam sodium treatment. Application of metam sodium through the drip irrigation system following a spring crop of root-knot nematode-resistant bell pepper should reduce severity of root galling and reproduction of M. incognita as well as increase fruit yield of fall-cropped cucumber.