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  • Author or Editor: J.D. Norton x
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Abstract

‘AU-Roadside’ is a new plum cultivar developed by the Dept. of Horticulture, Alabama Agricultural Experiment Station, Auburn Univ., for growing in areas where chilling of 700 hr of temperature below 7°C occurs. ‘AU-Roadside’ has produced high yields of excellent quality fruit where certain fruit problems and diseases occur.

Open Access

Linkage relationships among eight isozyme genes (Acp-3, Est-1, Est-5, Prx-1, Prx-2, Prx-3, Me, and Adh) and two morphological markers (Inh and Twh) were investigated in one F2 and two BC1 families of interspecific crosses between the American chestnut (Castanea dentata Borkh.) and the Chinese chestnut (C. mollissima Blume). Inh was consistently linked with Prx-1 and Est-5 in all families. In addition, four other gene pairs, Acp-3Inh, Acp-3Prx-1, Me–Inh, and Twh–Inh, were linked in one of the three families investigated. The two isozyme genes and two morphological marker genes were tentatively integrated into one linkage group with the gene order TwhInhPrx-1Est-5.

Free access

Abstract

Chinese chestnut, Castanea mollissima Bl., is resistant to chestnut blight incited by Endothia parasitica Murr., a disease which eliminated almost all American chestnuts, C. dentata (Marsh) Borkh. Two or three nuts are usually present in each bur of Chinese chestnuts; the better ones are excellent in quality. Chinese chestnuts grow over a large part of the United States; however, they seem best adapted to the southeastern region.

Open Access

On March 13-15, 1993 Alabama and much of the eastern United States experienced an unusually severe winter storm. This afforded the evaluation of plum cultivar production under cold stress. The highest yielding variety that bloomed before the storm was Bruce 12-4 with 28 kg/tree. Bruce 12-4 is noted for blooming over an extended period of time and producing very heavy yields. The average yield of the top five performers that bloomed after the storm was 51 kg/tree. The lowest temperature recorded at the test site, Shorter, AL was -5C.

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Of 153 plant introductions (PI), breeding lines, and commercial cultivars tested by mechanical inoculations in the greenhouse, only PI 482261-1, `Egun', PI 494528, PI 386026, and PI 386025 showed any resistance to the Florida strain of zucchini yellow mosaic virus. PI 482261-1 and `Egun' are Citrullus lanatus, the others are citron types, Citrullus colocynthis. This is the first report of resistance in PI 386026, PI 386025, and the cultivar `Egun'.

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In an anthracnose [Colletotricum obiculare (Berk. & Mont.) Arx.] screening test of 76 plant introductions (PIs), commercial Chinese watermelons [Citrullus lanatus (Thunb.) Matsum. & Nakai], and `Crimson Sweet', PI 512385 had the highest disease resistance with a mean rating of 4.5 (1= resistant, 9 = susceptible). In a second test with PI 512385, which included material with previously reported resistance (PIs 270550,326515, 271775,271779,203551, 299379, and 189225), and `Crimson Sweet' (susceptible control), PI 512385 had significantly higher resistance than `Crimson Sweet' but was not significantly more resistant than the other PIs evaluated. PI 512385 had a mean rating of 2.2 in the second test.

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Forty eight cultivars, species, and their progeny including Prunus americana P. angustifolia, P. cerasifera P. munsoniona, P. salicina, P. simoni, and P. triflora were evaluated for resistance to Xylella fastidiosa based on percent of scalded leaves and tree longevity. Observations indicate that resistance is heritable and controlled by recessive genes. Further, X. fastidiosa transmission was evaluated in plum and peach by chip and slip budding. Transmission as measured by enzyme-linked immunoabsorbant assay indicated that chip budding resulted in a higher level of transmission over slip budding in plum but not in peach. Neither Lovell nor Nemaguard rootstock had an effect on transmission.

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Detection of Xylella fastidiosa Wells et al. by enzyme-linked immunosorbent assay indicated that plums (Prunus hybrids) had higher absorbance values than peaches [Prunus persica (L.) Batsch]. The slip-budded trees had lower readings than those that were chip budded; however, the scion × method interaction was significant. Further comparison of slip vs. chip budding indicated that the lower absorbance value of slip budding occurred in plums only; there was no difference between budding methods in peach.

Free access