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  • Author or Editor: James M. Meyers x
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The toxic bait, Adios, was tested with the use of a trap crop in a field experiment at the Univ. of Nebraska during Summer 1998. The insecticide contains the secondary plant metabolites known as cucurbitacins that are highly attractive to the striped and spotted cucumber beetles, Acalymma vittatum and Diabrotica undecimuncata howardi, respectively. These beetles serve as the vector of the bacterial pathogen, Erwinia tracheiphila, which causes severe wilting and eventual death of susceptible cucurbits. The objective of the study was to determine whether treatments of Adios, when applied to a flowering trap crop of resistant squash plants, would lure the cucumber beetles away from the susceptible cucumber plants and reduce bacterial wilt. The study compared the effectiveness of a sprayed trap crop, the direct application of Adios to the cucumber plants and no treatment in a randomized complete-block design. A greater number of beetles were attracted to the sprayed and untreated cucumbers compared to the cucumbers surrounded by the treated trap plants. However, significant numbers of dead beetles were found near the sprayed cucumber plants. Untreated plants showed more feeding damage, diminished fruit quality, and an earlier observation date of wilt symptoms as compared to the other treatments. The treated trap plants and the direct application of Adios were effective in delaying infection in cucumbers compared to the untreated plants in the experimental plots. This treatment may be useful to home gardeners.

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Concentrations of aroma precursor compounds in ‘Riesling’ wine grapes (Vitis vinifera) are reported to correlate with fruit zone cluster exposure, although optimal cultural influences with respect to exposure timing and canopy assessment methods have not been established. To determine the impact of cluster exposure on concentrations of potential aroma compounds, correlations between light exposure metrics during the growing season and relative concentrations of eight representative aroma compounds at harvest were determined. The aroma compounds were carbon-13 (C13) norisoprenoids [1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), β-damascenone, and vitispirane], monoterpenes (linalool oxide, α-terpineol), and phenolics (4-vinylguaiacol, vanillin and eugenol). Cluster exposure was determined using metrics of varying spatial precision [percent interior cluster (PIC), cluster exposure layer (CEL), ln(CEL), cluster exposure flux availability (CEFA), and the percent ambient photosynthetic photon flux (PPF)] at two sites and two phenological stages (fruit set and veraison) in two consecutive seasons (2008 and 2009). Pairwise combinations of cluster exposure metrics and compounds resulted in 360 permutations, of which 22 were significant. Response data suggested that none of the compounds studied respond to variable cluster exposure levels below 20% of ambient sunlight (CEFA < 0.2), and that low cluster exposure may be particularly effective in minimizing C13 norisoprenoid concentrations at harvest. Yield components were also tested but found to have lower R 2 values compared with cluster exposure metrics. Active canopy management, in which vine vigor and fruit exposure are independently controlled, is likely to be more effective in influencing potential aroma compounds than selectively harvesting for naturally occurring variation in cluster exposure. In comparing the relative predictive strength among metrics, CEFA ≅ ln(CEL) > CEL > PIC ≅ percent PPF, suggesting that cluster exposure metrics with greater spatial sensitivity are more effective for establishing light response curves.

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To manage excessive vine vigor, Vitis vinifera L. ‘Cabernet franc’ grapevines were subjected to shoot wrap, shoot tuck, and hedge (control) techniques at one of two growth stages (shoot tips at 30 cm or at 90 cm above the top catch wire) in the Finger Lakes region of New York from 2016 to 2019. Shoot tuck and shoot wrap both reduced fruit zone lateral counts, with reductions up to 33% and 56% compared with the control, respectively. Shoot wrap reduced fruit zone lateral lengths by up to 50% and cluster compactness by up to 2.4 fewer berries per centimeter rachis. Although shoot wrap improved spray penetration to the clusters by up to 28% in one year of the study, enhanced point quadrat analysis indicated that occlusion layer number was not affected by the treatments. Shoot tip management treatments did not affect yield or fruit composition consistently. Phenological timing of shoot tip management had little impact on vine growth. Although the impacts of these modified shoot tip management practices on lateral emergence and cluster morphology were generally positive, the required hand labor to apply the treatments on a large scale may discourage the use of these management practices.

Open Access

An experimental vineyard was planted in Geneva, NY, in 2007 to determine the impact of training system [low bilateral cordon with vertical shoot positioning (LVSP), high wire bilateral cordon (HWC)], vine spacing (1.8 and 2.4 m), and root system [own-rooted, grafted onto ‘101–14 Mgt’ (Vitis riparia × Vitis rupestris)] on vine growth, yield, fruit composition, and wine quality of the recently-released winegrape ‘Noiret’ (Vitis hybrid). Yield components were generally unaffected by training system in 2009, but vines spaced at 2.4 m had about six fewer clusters per meter of canopy, lower pruning weights by 0.24 kg·m−1, and clusters that were 0.01 kg greater in mass compared with vines spaced at 1.8 m. In 2010, HWC yielded 0.98 kg·m−1 more than LVSP, and had a higher crop load ratio by 0.8. Larger vine spacing increased yield by 0.32 kg·m−1 and increased crop load ratio by 0.3. Grafted vines increased yield by 0.36 kg·m−1 and crop load ratio by 0.3. Training system and vine spacing had minimal impact on fruit composition in both years. Rank sum analysis indicated a consumer preference for the aroma of wines from the HWC/2.4-m treatment compared with wines from the LVSP/1.8-m treatment in 2009, and a consumer preference for the aroma of wines from the HWC/1.8-m treatment compared with wines from the LVSP/1.8-m treatment in 2010. Results suggest that the LVSP system is not a suitable choice for vigorous ‘Noiret’ vines because of low yields, low crop load ratios, and low preference rankings of LVSP wines by the consumer sensory panel.

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Crop load management treatments were applied to ‘Seyval Blanc’ grapevines (Vitis hybrid) as a 2 × 2 factorial design: no shoot thinning (ST)/no cluster thinning (CL) (i.e., control), ST combined with CL (ST + CL), ST only, and CL only. All treatments reduced yield and crop load (yield/pruning weight) in 2009 and had a smaller impact in 2010 due to the carryover effect of previous year treatments on crop potential. Soluble solids were improved by up to 3.2% by the ST + CL treatment in 2009, but were not impacted by treatments in the second year when the range of yield was smaller and the ripening conditions more favorable. Rank sum analysis for the 2009 vintage indicated that wines produced from the CL treatment were preferred by the sensory panel compared with the control wine, but there were no differences in consumer preference for wines produced in the 2010 season. Grower preferred price in 2009 (required to compensate the grower for labor costs and lost yield) increased from $556/t in the control to $824/t in the CL treatment, an increase which could be justified by the demonstrated consumer preference for the CL wine. Grower preferred price was $1022/t in the ST + CL treatment in 2009, a price increase that was not justified by a demonstrated consumer preference for the wine. In 2010, grower preferred price ranged from $541/t for the control to $610/t for the ST + CL treatment, an unjustified increase based on the lack of demonstrated consumer preference for the wines.

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