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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).
Abstract
Twenty-two sweet potato (Ipomoea batatas (L.) Lam.) breeding lines and 19 open-pollinated offspring from each were used to estimate the heritabilities of 7 measures of soil insect injury. Four measures of injury by the wireworm, Diabrotica spp., and Systena spp. (WDS) complex and h2 (± SE) were: percentage of roots injured, 0.45 ± 0.12; holes per root, 0.32 ± 0.09; severity index, 0.37 ±0.11; and damage score, 0.39 ± 0.17. Two measures of injury by the sweetpotato flea beetle, Chaetocnema confinis Crotch, and h2 were: percentage of roots injured, 0.40 ± 0.07, and tunnels per root, 0.25 ± 0.08. The h2 of percentage of roots injured by all insects was 0.51 ± 0.12. The percentage measures were more easily obtained and were as effective as the other measures under the conditions of natural infestation that occurred in this test. Further advances in selection for high levels of resistance to soil insects are possible within the breeding materials tested.
Abstract
A parent-offspring test of 21 sweet potatoes (Ipomoea batatas (L.) Lam.) and 25 open-pollinated offspring from each provided heritability estimates (h2 ± SE) for root fiber (0.47 ± 0.04), weight (0.41 ± 0.04, shape (0.50 ± 0.05), cracking (0.37 ± 0.04), and sprouting (0.37 ± 0.02). These characters were sufficiently independent to allow selection of one, or of any combination simultaneously, without adverse effects on the others.
Abstract
Soil insect root injury to resistant sweet potato [Ipomoea batatas (L.) Lam.] cultivars ‘Regal’ and ‘Southern Delite’ was compared to injury to ‘Jewel’ and ‘Centennial’ in trials with the resistant-standard W-13 and the susceptible-standard SC 1149-19. Injury by three groups of insects was evaluated: the wirewoom-Diabrotica-Systena complex (WDS), which includes the southern potato wireworm (Conoderus falli Lane), the tobacco wireworm (C. vespertinus Fabricius), the banded cucumber beetle (Diabrotica balteata LeConte), the spotted cucumber beetle (D. undecimpunctata howardi Barber), the elongate flea beetle (Systena elongata Fabricius), the pale-striped flea beetle (S. blanda Melsheimer), and S. frontalis Fabricius (a flea beetle); the sweet potato flea beetle (Chaetocnema confinis Crotch.); and a white grub (Plectris aliena Chapin). Relative control estimates were obtained by comparison to the susceptible standard. ‘Regal’ and ‘Southern Delite’ provided good control of all three insect groups with control of all insect injuries of 79.2% and 81.0%, respectively. ‘Jewel’ and ‘Centennial’ were resistant to the sweet potato flea beetle and sustained less damage by WDS than the susceptible standard, but would still be classed as susceptible to WDS. ‘Centennial’ was as susceptible to the white grub as SC 1149-19. The levels of resistance demonstrated for ‘Regal’ and ‘Southern Delite’ would provide growers an alternative to insecticides for the control of these insects.
Abstract
Root knot caused by the southern root-knot nematode (Meloidogyne incognita (Kofoid & White) Chitwood) is a serious disease of sweet potato (Ipomoea batatas (L.) Lam.) in most production areas of the U. S. and especially in the southern states (3). Considerable variation in pathogenicity of this obligate parasite on sweet potato was reported by Giamalva et al. (1) in 1963. In 1973, Martin and Birchfield (2) reported the discovery of a race of M. incognita that was highly virulent and reproduced abundantly on a sweet potato line, L4-73, that had been established as resistant to root-knot nematode populations commonly found in Louisiana. This strain of M. incognita, herein designated the “resistance breaking” (RB) race, was provided through the courtesy of Dr. W. J. Martin of the Department of Plant Pathology, Louisiana State Univ., Baton Rouge. These findings have caused considerable concern about the future of breeding for root knot resistance in sweet potato, since the existence of RB races makes the work much more difficult and complicated. A breeding line of sweet potato (W-51) was developed at the U. S. Vegetable Laboratory, in cooperation with Clemson University, that is resistant to both the common and the RB race of root-knot nematodes (M. incognita). It also carries resistance to fusarium wilt (Fusarium oxysporum f. sp. batatas (Wr.) Snyd. & Hans.) and the sweet potato flea beetle (Chaetocnema confinis Crotch.). W-51 is being released for use as a root knot resistant parent in sweet potato breeding programs.
The test involved the use of a control (untreated), an entomopathogenic nematode (Steinernema carpocapsae), a granular insecticide (Dyfonate 2.24 Kg ai/ha) in combination with 7 sweetpotato cultivars having varying levels of resistance and susceptibility to soil insect damage. The parasite was applied three times at monthly intervals (67/cm2). The parasite or insecticide did not reduce root injury by soil insects as compared to the control (untreated). Wireworms, Diabrotica sp. and Systena sp. damage in the resistant cultivars Regal, Southern Delite, Excel and Resisto was less than for the susceptible cultivars (SC–1149-19, Jewel and Centennial). Sweetpotato flea beetle resistance was observed for all cultivars except SC–1149-19 which was susceptible. In this test resistant cultivars were more effective in reducing soil insect damage than the biological or chemical control methods.
The test involved the use of a control (untreated), an entomopathogenic nematode (Steinernema carpocapsae), a granular insecticide (Dyfonate 2.24 Kg ai/ha) in combination with 7 sweetpotato cultivars having varying levels of resistance and susceptibility to soil insect damage. The parasite was applied three times at monthly intervals (67/cm2). The parasite or insecticide did not reduce root injury by soil insects as compared to the control (untreated). Wireworm, Diabrotica and Systena damage in the resistant cultivars Regal, Southern Delite, Excel and Resisto was less than for the susceptible cultvars (SC–1149-19, Jewel and Centennial). Sweetpotato flea beetle resistance was observed for all cultivars except SC–1149-19 which was susceptible. In this test resistant cultivars were more effective in reducing soil insect damage than the biological or chemical control methods.
Abstract
‘Patriot’ is a determinate tomato (Lycopersicon esculentum Mill.) with excellent fruit color, developed primarily as a fresh-market or home-garden type. It is resistant to root knot and fusarium wilt.