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  • Author or Editor: Bruce P. Bordelon x
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Monoterpenes are organic compounds found in high quantities in certain wine grape varieties, such as Riesling, Gewürztraminer, and muscat-flavored varieties. These compounds exist in free and glycosidic form, and produce the characteristic aromas of such varieties. Traminette, released in 1996 as NY65.0533.13, is a cross between Joannes Seyve 23.416 and Gewürztraminer. This variety may be an alternative to Gewürztraminer in areas where cold temperatures prevent cultivation of such cold-tender varieties. The objective of this study is to determine the extent of which sunlight exposure influences monoterpene production in `Traminette'. Various exposure levels were obtained through synthetic coverings and ambient shading. Fully exposed clusters on a vertically shoot positioned canopy received 55% of ambient light whereas clusters with 50 and 70% shade cloth received 14.7 and 5.3%, respectively. Heavily shaded clusters (3+ leaf layers) received 2% of ambient light, and fully covered clusters received no light from véraison to harvest. Despite large differences in exposure level, cluster temperatures did not differ significantly between treatments. Results of monoterpene quantification show potentially volatile terpene (PVT) levels were 10-fold greater than free volatile terpene (FVT) levels in all treatments. PVT levels differ significantly between exposure groups in all locations at harvest, with exposed fruit having the highest concentration (6.5-7.5 mg L-1). Heavy and moderate shade fruit had 25% lower PVT levels compared to exposed fruit. Fully covered clusters had 34% less PVT, whereas 50 and 70 shade cloth clusters were 20% lower than exposed. Subsequent years of research will further validate preliminary findings of this study.

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Grapevines (cv. Steuben) were field-grown for 1 year to determine the effects of pruning and grow tube use on vine growth. Plots were grown on Crosby-Miami silt loam soils, trickle irrigated as needed to ensure adequate moisture, and provided a 3-ft band of weed control on each side of the row. Vines were trained onto a 5-ft. tall-trellis using the following techniques: 1) pruned to a single shoot and placed in a grow tube supported by a bamboo stake, 2) pruned to a single shoot and trained on a bamboo stake without a grow tube, or 3) left unpruned and trained on four strings radiating out from the vine to the top wire. At the end of the growing season, the vines were destructively sampled for leaf area, total shoot growth, average internode length, shoot diameter, top growth dry weight, and root system dry weight. The results indicate that pruning vines to a single shoot significantly reduced overall vine growth, whether a tube was used or not. Vines trained to single shoots and grown with or without grow tubes did not differ significantly for the various parameters measured. Unpruned vines produced nearly three times more leaf area, more than two times more total shoot length, and more than two times more top dry weight and root dry weight than the other treatments. A sub-set of these vines will be grown for one more season to determine if the negative effects of pruning and/or tubes will effect vine size after a second season.

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In a previous study to determine the feasibility of using herbicide desiccated cover crops for weed suppression during vineyard establishment, we found that weed suppression is excellent for about 6 to 8 weeks after desiccation in fall-planted rye. By the end of the season, however, weed growth in rye plots was similar to weedy control plots. Vine growth was reduced in rye plots compared to weed-free bare ground plots. Because of the experimental design, no follow-up weed control was performed in the rye plots and weeds eventually became well-established. So, it was impossible to determine if reduced vine growth was due to weed competition or allelopathy from the rye residues. A second study was conducted to determine the effects of follow-up weed control (with glyphosate) in fall-planted rye plots and weedfree bare ground plots. Results indicate that vine shoot number, shoot length, leaf area, and top growth dry weight was greatest in weedfree bare ground, less, but not significantly so in rye with follow-up weed control, and significantly less in rye without follow-up weed control. Root dry weight was reduced in rye with and without follow-up weed control compared to weedfree bare ground. Root dry weight was reduced 37% in rye with follow-up weed control and 63% in rye without follow-up weed control compared to weedfree bare ground. These results suggest that weed competition is not the primary cause of vine growth reduction in herbicide desiccated rye cover crops, so there is likely allelopathic effects of the rye residues on grapevines, which would limit using rye as a desiccated cover crop during vineyard establishment. However, there may be some value in using rye in established vineyards to reduce vigor.

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Use of in-row cover crops for weed management in first-year vineyards was investigated in two studies. In the first study, rye (Secale cereal L. 'Wheeler') was fall-planted, overwintered, then managed by three methods before vine planting. Rye was either herbicide-desiccated with glyphosate and left on the surface as a mulch, mowed, or incorporated into the soil (cultivated). Weed density and growth of grapevines (Vitis spp.) were evaluated. Herbicide desiccation was superior to the other methods for weed suppression, with weed densities 3 to 8 times lower than for mowed or cultivated plots. Vine growth was similar among treatments, but the trend was for more shoot growth with lower weed density. In a second study, four cover crops, rye, wheat (Triticum aestivum L. 'Cardinal'), oats (Avena sativa L. 'Ogle'), and hairy vetch (Vicia villosa Roth), were compared. Wheat and rye were fall- and spring-planted, and oats and vetch were spring-planted, then desiccated with herbicides (glyphosate or sethoxydim) after vine planting and compared to weed-free and weedy control plots for weed suppression and grapevine growth. Cover crops provided 27% to 95% reduction in weed biomass compared to weedy control plots. Total vine dry mass was highest in weed-free control plots, was reduced 54% to 77% in the cover crop plots, and was reduced 81% in the weedy control. Fall-planted wheat and rye and spring-planted rye plots produced the highest vine dry mass among cover crop treatments. Spring-planted rye provided the best combination of weed suppression and vine growth. Chemical names used: N-(phosphonomethyl) glycine (glyphosate isopropylamine salt); 2-[l-(ethoxyimino)butyl]5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

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Various plant growth regulators were used to stimulate endosperm and embryo development in four stenospermic grape cultivars. Five antigibberellins were applied to clusters at 1000 and 100 ppm two weeks prior to bloom. Two cytokinins were applied at 1000, 500, and 250 ppm 20 days after bloom. Combinations of the treatments were also made. Data collected included: 1) cluster weight, 2) berry weight, 3) number of `sinker' and `floater' seed traces, 4) `sinker' weight and 5) percent germination. Significant differences were found among treatments for some of the variables. Differences also occurred among cultivars. Percent germination was greater for cultivars with large seed traces. The technique appears to have promise as an alternative to ovule culture/embryo rescue for intercrossing stenospermic grapes.

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Timing and concentration of GA applications were evaluated for berry thinning and sizing on `Vanessa'. Mid-bloom applications at 0, 5, 10, 15, 20 and 30 ppm GA were tested for berry thinning. Post-bloom applications of 0, 25 and 50 ppm GA at 7, 12, 16 and 21 days past mid-bloom were tested for berry sizing. None of the mid-bloom (thinning) treatments significantly reduced the number of berries per cluster or cluster compactness. Mid-bloom applications at 15, 20 and 30 ppm GA significantly increased berry weight. Post-bloom (berry sizing) treatments significantly increased berry weight with each increase in GA concentration for each time of application. The number of berries per cluster was significantly increased by sizing sprays at 7 and 12 days, but not at 16 or 21 days past mid-bloom. Cluster weight was significantly increased by 25 and 50 ppm GA applied at 7, 12 and 16 days past mid-bloom. All post-bloom applications significantly reduced the number and weight of shot berries.

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A method for extraction of high quality DNA from four Opuntia sp. and other cacti using a hexadecyltrimethylammonium bromide (CTAB) method is described. These plants typically contain high levels of mucilages, complex polysaccharide compounds that bind water, thus preventing DNA extraction by common miniprep methods. The method involves adjusting the amount of tissue used according to species and age, followed by processing in an extraction buffer to separate coarse material. Extended centrifugation and digestion time in a separation buffer with CTAB (2%) was used. Exposing tissue to both buffers maintained polysaccharides in solution and allowed easier recovery of the aqueous phase that contains the DNA. We found that 5-8 g were needed to obtain up to 153 μg·g-1 of DNA from tender tissue. Old tissue yielded 26% less. Extraction of DNA from 5-g samples of tender tissue of the ornamental cacti Stenocereus sp., Cleistocactus sp., and Echinocereus sp. was successful. For these species, average yields ranged from 25 to 53 μg per sample. The DNA obtained was suitable for polymerase chain reaction (PCR) amplification, producing clear, distinctive, and reproducible banding patterns useful for a variety of applications.

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The influence of in-row plant spacing on the yield and fruit size of `Blueray' (erect growing) and `Bluecrop' (spreading) highbush blueberry (Vaccinium corymbosum L.) was studied. Plants of both cultivars, spaced at 0.61 m within the row, had significantly higher yields per hectare than plants grown at wider spacings (0.92 and 1.22 m) in each of five harvest years. On a per-plant basis, however, plants spaced at 1.22 m had higher yields in the last two harvest years of the experiment than plants spaced more closely, which indicated that interplant competition reduced per-plant yields of closely spaced plants as plants grew larger. Over the 5-year harvest period, plots with 0.61-m plant spacing produced a cumulative total yield of 17.24 t·ha more than plots with the conventional 1.22-m spacing. Plant spacing did not affect fruit size in this experiment.

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The influence of in-row plant spacing on highbush blueberry yield and fruit size was studied on two cvs., `Blueray' (erect growing) and `Bluecrop' (spreading). Plants of both cvs. spaced at 0.6lm in-row significantly outyielded plants at wider spacings (0.92, 1.22m) in each of the five harvest years when based on per hectare yields. On a per plant basis, however, plants spaced at 1.22m outyielded closer spaced plants in the last two harvest years of the experiment, indicating that interplant competition was reducing per plant yields on close spaced plants as plants grew larger. Over the 5-year harvest period, plots with 0.61m plant spacing produced a cumulative total yield increase of 17239 kg/ha more than plots with the conventional spacing of 1.22m. There were no effects of plant spacing on fruit size in the experiment.

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Use of high tunnel crop production is expected to increase to meet the growing demand for locally produced fresh market vegetables. These structures have the potential to offer many production benefits; however, managing soil quality in these structures is challenging and work in the area is limited. In this 3-year study, we compared the impacts of organic and inorganic fertility amendments on soil quality, nutrient availability, and the productivity of chard (Beta vulgaris L.) and sweet peppers (Capsicum annuum L.) produced in high tunnel and open field systems. Fertility amendments included a green manure treatment [hairy vetch (Vicia villosa Roth) and dehydrated alfalfa meal], partially composted and pelletized chicken litter, urea, and an unfertilized control. Chard was grown in 2011, and peppers were grown in 2012 and 2013. Soil nutrients, microbial activity, active carbon, pH, electrical conductivity (EC), total soil organic matter, and yield were quantified. Chard yield was lower in the high tunnel compared with the open field in 2011, but pepper yield was greater in the high tunnel in 2012 and 2013. Productivity of chard was lower in the green manure compared with urea in 2011 across high tunnel and open field production systems, but no difference in pepper yield was observed between plants receiving fertility inputs in either 2012 or 2013. Repeated application of green manure and chicken litter resulted in soils with increased microbial activity and active carbon, but the green manure was the only treatment successful at accruing carbon in the high tunnel over time. High tunnel production resulted in greater EC compared with the open field, but levels were not considered inhibitory for chard or peppers. High tunnels can increase vegetable crop productivity in the midwest United States, and organic fertility amendments can improve soil quality as measured by soil microbial activity and active carbon in high tunnel and open field production systems.

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