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- Author or Editor: P. D. Dukes x
There are four known physiological races of the southern root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood]. Races are designated I through 4 and their identifications are based soley on differential hosts. These race problems as related to breeding sweetpotato for resistance to attack by all races are reviewed and discussed. Data are presented showing the reactions of selected cultivar and breeding clones of sweetpotato to all four races. The reactions of races 1 and 3 are generally well—known. Races 2 and 4 apparently are spreading and becoming more numerous in the southern states where soybean and tobacco are grown. Comparative disease indices are presented showing that generally sweetpotatoes were less susceptible to races 2 and 4. However, there were some notable exceptions, for example, `Sulfur' and `Beauregard' were equally susceptible to all races. High resistances to attack by races 2 and 4 were found in `Sumor', `Nemagold', `Excel', W-241 and others.
The Agricultural Research Service of the United States Department of Agriculture announced the release of `Bettergro Blackeye' southernpea on 24 July 1991. The new cultivar is well adapted for production throughout the southern United States where it can be expected to produce excellent yields of high quality, blackeye-type peas. `Bettergro Blackeye' outyielded the `Pinkeye Purple Hull-BVR' check in the 1986, 1987, 1988, and 1989 Regional Southernpea Cooperative Trials by 34.8, 14.3, 12.6, and 20.9%, respectively. Canned samples of fresh `Bettergro Blackeye' peas scored well in three years of quality evaluation tests. The new cultivar is resistant to the cowpea curculio, the major insect pest of the southernpea in southeastern production areas, and root knot, a severe root disease incited by several species of the root-knot nematode. `Bettergro Blackeye' plants have a greater tendency to produce a second crop than plants of most southernpea cultivars.
A useful and novel cayenne pepper (Capsicum annuum L.) breeding line has been released by ARS, USDA, U. S. Vegetable Laboratory. This new Line, designated and tested as PA-136, has a high level of tolerance to massive infection by root-knot neamtodes (Meloidogyne spp.) to which it is susceptible. PA-136 has proven to be useful as a host for the abundant production of eggs for several Meloidogyne species, including all 4 races of M. incognita. Availability of large quantities of egg inoculum of these obligate parasites is a pre-requisite for successful and efficient breeding for root-knot resistance. PA-136 plants are vigorous, strong and uniformly branched, and reach a height of about 60 cm. The line has many good horticultural traits, including high yield, deep red fruit color, and high pungency. PA-136 is stable for all traits needed for the production of large numbers of viable eggs. Eggs are easily collected when needed from fresh roots using the Hussey-Barker extraction procedure (Plant Dis. Reptr. 57:1025-1028. 1973).
The USDA has released a new cream-type southernpea [Vigna unguiculata (L.) Walp.] cultivar that is well adapted for productionthroughout the southern United States. The new cultivar, named `Tender Cream', is the product of a backcross breeding procedure to transfer the dominant Rk gene for root-knot nematode resistance from `Floricream' into `Carolina Cream'. `Tender Cream' is resistant to cowpea curculio, root-knot nematodes, southern bean mosaic virus, cercospora leaf spot, southern blight, rust, and powdery mildew. `Tender Cream' outyielded the cream control in the 1992, 1993, and 1994 Regional Southernpea Cooperative Trials by 5.4%, 11.0%, and 18.8%, respectively. It outyielded its root-knot-nematode-susceptible `Carolina Cream' isoline by 22.3% in a replicated 1994 test conducted in a field infested with a natural population of the southern root-knot nematode. Canned samples of fresh `Tender Cream' peas scored well during 3 years of testing at the Univ. of Arkansas.
The southern root-knot nematode, Meloidogyne incognita [(Kofoid & White) Chitwood], causes serious economic losses to melon (Cucumis melo L.) production in the United States. The present study was conducted to determine if separable differences in nematode resistance of Cucumis melo could be found at some inoculum level. Five C. melo lines were compared with Cucumis metuliferus Naud. (C701A), a highly resistant species, for root necrosis, galling, egg mass production, and reproduction when inoculated at 0, 500, 1000, 2000, or 5000 nematode eggs per plant. Using these criteria, melon line C880 inoculated with 1000 eggs per plant was highly susceptible, while PI140471, PI 183311, and the cultivars Chilton, Georgia 47, Gulf Coast, Planters Jumbo, and Southland were less susceptible. In greenhouse tests with an inoculum level of 1000 eggs per plant, low levels of resistance were evident. A thorough screening of the available germplasm against M. incognita may identify higher levels of root-knot nematode resistance for incorporation into improved melon cultivars.
Bettersnap southernpea (Vigna unguiculata) was developed as a replacement for the popular cultivar Snapea. The new cultivar is well adapted for production throughout the southern United States where it can be expected to produce excellent yields of edible pods or snaps. Bettersnap is resistant to root knot, a severe root disease incited by several species of the root-knot nematode (Meloidogyne spp.), and blackeye cowpea mosaic virus, the major pathogen of southernpea in the United States. Observations of natural epiphytotics indicate that the cultivar is also resistant to scab (Cladosporium vignae) and cercospora leaf spot (Cercospora cruenta). The new cultivar has the same maturity and high yield potential as Snapea. Bettersnap is recommended for use as a home garden cultivar for spring, mid-season, and fall plantings. It is particularly recommended for trial as a commercial processing cultivar for the production of the immature green pods used for the ``snap” component of the popular mixed packs of fresh peas and green snaps.
The Agricultural Research Service of the United States Department of Agriculture announced the release of Carolina Crowder southernpea on 12 October 1990. The new cultivar is well adapted for production throughout the southern U.S., where it can be expected to produce excellent yields of high quality, crowder-type peas. Carolina Crowder is resistant to the cowpea curculio, the major insect pest of the southernpea in southeastern production areas; blackeye cowpea mosaic virus, an important virus pathogen of southernpea in the United States; and root-knot, a severe root disease incited by several species of the root-knot nematode. Canned samples of fresh Carolina Crowder peas scored well in three years of quality evaluation tests. Pod color is a brilliant red at early green-shell maturity and a brilliant red heavily shaded with cranberry colored pigment at optimum green-shell maturity. The attractive pod color should make Carolina Crowder an excellent candidate for fresh market use. Carolina Crowder plants have a greater tendency to produce a second crop than plants of most southernpea cultivars.
The results of recently completed genetic studies indicate that the green cotyledon trait exhibited by the southernpea [Vigna unguiculata (L.) Walp.] cultivar Bettergreen is conditioned by a single recessive gene. This gene, designated green cotyledon and symbolized gc, is neither allelic to nor linked with the gt gene that conditions the green testa trait exhibited by the cultivar Freezegreen. The color of seeds harvested from plants homozygous for both the gc and gt genes is superior and more uniform than the color of seeds harvested from either Better-green or Freezegreen plants. This observation suggests that efforts should be initiated to study the feasibility of using both the gc and gt genes to develop cultivars that produce seed with an enhanced, persistent green color. The selection methodology for both seed traits is rapid and reliable. The green cotyledon trait can be selected in the seed stage.
‘Kiawah’ (kee'-a-waw) southernpea [Vigna unguiculata] (L.) Walp.] has been released by ARS/USDA as a replacement for ‘Pinkeye Purple Hull,’ a widely grown commercial cultivar. ‘Kiawah’ is well adapted for production throughout the southeastern United States where it can be expected to produce excellent yields of high quality, pinkeye-type peas. The major attribute of ‘Kiawah’ is its high level of resistance of root knot, a major root disease of southernpea incited by several species of the root-knot nematode genus Meloidogyne. The new cultivar is named in honor of the friendly Kiawah Indian Tribe, which welcomed and helped the original English settlers of Charleston, S.C.
The ARS/USDA has announced the release of southernpea [Vigna unguiculata (L.) Walp.] breeding lines US-311 and US-427. US-311 is an early maturing, pinkeye type pea, and US-427 is a root-knot nematode (Meloidogyne spp.) resistant, brown crowder type pea. Both lines are near cultivar quality, and each is recommended for use as parental material in breeding programs.