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  • Author or Editor: M.A. Wilson x
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Abstract

Lateral budbreak was increased significantly on ‘Welkeri’ dieffenbachia [Dieffenbachia maculata (Lodd.) G. Don] with foliar applications of 6-benzylamino purine (BA) at 500,1000, and 2000 mg/liter. Sodium 2,3:4,6-bis-0-(1-methylethylidene)-a-L-xylo-2-hexulofuranosonic acid (dikegulac) at 1000, 1500, and 2000 mg/liter and (2-chloroethyl)phosphonic acid (ethephon) at 500, 1000, and 2000 mg/liter had no effect on branching. Plant height was unaffected by application of growth regulators although moderate foliar necrosis was caused by the highest rate of BA.

Open Access

The origin and development of somatic embryos from petiole sections of Regal geranium (Pelargonium ×domesticum Bailey `Madame Layal') were studied using time-series sections at days 0, 4, 8, 14, and 24. Somatic embryos originated as early as day 4 of culture. The proembryo stage resembled that of a zygotic embryo and the somatic embryos developed through the globular, heart-torpedo, and cotyledonous stages characteristic of in vivo zygotic embryogenesis. A suspensor-like structure was observed with some somatic embryos but this was not consistent. Strong evidence is presented to suggest that somatic embryos arose from single subepidermal parenchyma cells.

Free access

Extension postharvest quality maintenance programs in North Carolina were significantly enhanced by engineering inputs and Exxon violation escrow funds. Equipment and storage designs and recommendations have provided tangible results for North Carolina horticultural crops producers and shippers, including “Cool and Ship,” a portable, pallet-size forced-air cooling system, thermal storage immersion hydrocooling systems, and the horizontal air flow sweetpotato curing and storage system. Impacts include: 30% to 50% blueberry and strawberry loss reductions using forced-air cooling; and 20% to 30% sweetpotato packout rate increases when cured and stored with the new system. Useful materials include a video on cooling options, a computer decision aid for precooling, a storage poster, and more than two dozen publications on Maintaining the Quality of North Carolina Fresh Produce.

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A three year study involving solar heating of soil (soil solarization) with clear polyethylene mulch demonstrated for two years, control of root-knot nematodes (Meloidogyne incognita). The population of M. incognita was reduced >90% in the 0-30cm depth of solarized soil. The number of eggs per gram root recovered and the root gall index from `Georgia-Jet' sweetpotatoes were reduced (92-98%) by soil solarization. Growth and yield were enhanced in solarized soil. The beneficial effects of solarization was observed in the second year following two additional cropping cycles of collard greens and sweetpotatoes.

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Abstract

The interaction between Cytospora leucostoma (causal agent of peach canker) and host-phenolic compounds in dormant peach trees [Prunus persica (L.) Batsch] was examined. Initially, inoculated samples had significantly higher phenolic levels than uninoculated samples. The levels in inoculated samples decreased dramatically in tissues closest to the point of inoculation, however, while the phenolic levels in uninoculated samples remained relatively stable through time. The data suggested that C. leucostoma degraded host-phenolic compounds. Maximum phenolic enrichment was observed in the branch collar region of the main stem of inoculated samples. It was concluded that the presence of C. leucostoma in host tissue played a significant role, over and above the wounding response, in establishing levels of host-phenolic compounds. Levels of phenolics in host tissue seemed to increase in advance of the fungus and this increase may function as a mechanism that slows the pathogen's advance.

Open Access

Flavorcrest, Camden. C. L. Wilson, Loring, Elberta, Summergold and Harken peach varieties were inoculated and naturally infected with Monilinia fructicolo after ultraviolet light irradiation (W-C 254nm) showed increased resistance to brown rot disease. Although dosages ranged from 0 to 20 KJ/m2. 7.5 KJ/m2 was considered the most effective for the peach varieties tested. Pretreatment of peaches by field spraying or dipping into a benomyl fungicide showed no significant differences between non-treated and UV-C treated peaches. However. a combination of a low dose of benomyl (.15g/L) 3 days following UV-C treatment showed a synergistic effect on brown rot reduction when compared to Peaches treated with UV-C alone and a greater reduction of brow rot than benomyl control.

Free access

In 1988 and 1989 a muscadine vineyard at Tuskegee, Alabama was treated by post soil solarization (PSS) (covering of moist soil around muscadine plants with clear polyethylene plastic mulch to achieve high soil temperature) for 30 and 75 days, respectively. The average soil temperature in 1989 of 50 and 35 C at 5cm depth for solarized and bare soil, respectively during PSS. The results showed no visible detrimental effect on `Carlos' muscadine (Vitis rotundifolia) from the increased heating of the soil. And the grape plants grown in solarized soils showed increases in growth response e.g. increased yield, revitalization of new softwood vines, vine weight/plant, etc. Uneven ripening of muscadine grapes was reduced on plants grown in PSS over bare soil as indicated by the increases in the percent soluble solids content of grape berries.

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TU-155 and Georgia-Jet early, TU-1892 and Carver late maturing sweet-potato cultivars. were evaluated in the field to determine the effect of flower removal (FR) would have on marketable storage, root numbers and yield. Other parameters measured were leaf area and numbers, plant fresh and dry weight. Plants were sampled at 57 and 71 days after transplanting (DAT). All flowers were hand removed and the 1st harvest began 45 days DAT for the early and at 60 DAT for the late maturing cultivars. All flower harvests concluded 22 days after 1st harvest began and roots were harvested 120 DAT. There was significant differences among cultivars for total flower production with N-1892 and Georgia-Jet having the highest flower production. FR treatments for N-155 and Georgia-Jet showed significant increases for plant dry weight, leaf area and numbers 71 DAT while Carver and TU-1892 showed no significant differences for the same sample period. Marketable root numbers were not significantly affected by FR but marketable yields for all cultivars were. Overall, the cultivars showed variation both within and among maturity groups in their response to FR treatments, for example N-155 had a 39% compared to 3% increase for Georgia-let while Carver had a 15% increase in marketable yield compared to 5% for TU-1891.

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A study was conducted in 1991 to determine the effect high soil temperatures would have on `Clemson Spineless' okra plants transplanted into field plots during 60 days of active soil solarization (solar heating of the soil using clear plastic during the summer period). Solarized plots were planted to a winter cover crop which served as an organic amendment, which was rototilled into the top 15 cm of the soil before solarizing. Okra transplants were planted on the outer edges of the plots one month after the solarization process commenced and drip irrigated. Three weeks (wk) after transplanting, a complete fertilizer at the rate of 200 parts per million was applied to the plots giving the following treatment combinations: solarized non-fertilized control (SNF), non-solarized non-fertilized control (NSNF), solar fertilized (SF). and non-solarized fertilized (NSF). Results showed that the increased soil temperature did not have any deleterious effect on the okra plants grown in SNF or SF plots. However, plants grown in SF plots suffered severe fertilizer bums which affected plant density and yield. This indicated a rapid breakdown of soil organic matter provided sufficient nutrients to sustain a late-season crop of okra. Plant height, marketable yield vegetative branching and income generated were greater in SNF compared to SF, NSF and NSNF plots, respectively.

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An early planting (January) of 8 wks. old collards (Brassica oleracea (L) var. acephala `Georgia Collards') and subsequently followed by `Crimson Sweet' watermelon transplants (April) on clear and black polyethylene mulches and bare soil plus VisPore row cover (VCM, VBM, VBS), clear and black polyethylene mulches and bare soil (CM, BM, BS) in combination with drip irrigation were transplanted on the same plots. Marketable yield of collards (March) was significantly greater for mulched and row cover treatments than bare soil. Watermelon (harvested June 7th, 1990) total and marketable numbers and yield were significantly greater when grown on mulched treatments than bare soil. Mono-cropping of watermelon were profitable under VCM, VBM, CM and BM treatments and collards when grown as a mono-crop was not profitable under any system. By sharing the costs of production under a double-cropping system the profitability of watermelons increased when grown under VCM, VBM, CM, BM VBS and for collards under VCM and VBM treatments.

Free access