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Jean Pierre Kapongo, P.G. Kevan, and J.H. Giliomee

in the 1980s ( White and Elson-Harris, 1992 ). In South Africa, C. capitat a (Wiedemann) infests fruit trees and vegetables and is the only dipteran pest that occurs in vineyards ( ARC, 2001 ; Kapongo and Giliomee's personal field survey 1999

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Lindsay M. Jordan, Thomas Björkman, and Justine E. Vanden Heuvel

Traditionally, the soil directly beneath vines in wine grape vineyards is kept vegetation free to eliminate competition for water and nutrients. In the northeastern United States, bare soil is typically maintained beneath vines in vineyards with

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C.E. Elmore, D.R. Donaldson, and J.A. Roncoroni

Cover crops are planted between vineyard rows to control erosion, maintain organic material and influence pest management. Planted cover crops are preferable to resident vegetation (weeds) because they can be selected for beneficial characteristic. Sethoxydim and fluazifop-butyl alone and in combination with 2,4-D were applied in December 1988 and 1989 to release Festuca megalura (Zorro fescue). Untreated plots were mowed to maintain vegetation. Frequency, percent cover and biomass of the vegetation was evaluated to determine species shift. The vegetation was composed mainly of: 1. Festuca megalura, Poa annua with other grasses in minor amounts; and 2. Stellaria media, Centaurea solstitialis, Erodium botrys and Erodium cicutarium

Following sethoxydim or fluazifop-butyl treatments, annual grasses other than Festuca megalura and Poa annua were reduced but Centaurea sp. increased over the length of the experiment. Treatments containing 2,4-D Centaurea and Erodium spp. declined in both frequency and percent cover. The desirable cover crop species (Festuca megalura) increased in all treated plots. No species shift was observed in the mowed treatments. Two applications of selective post-emergence herbicides maintained shift of species over the 5 years of the study.

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Anil Shrestha, S. Kaan Kurtural, Matthew W. Fidelibus, Geoffrey Dervishian, and Srinivasa Konduru

Market forces and environmental considerations have encouraged some California grape growers to adopt organic management practices. In 2008, there were an estimated 23,000 acres of organic vineyards statewide ( Klonsky, 2010 ). Weed management

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S. Kaan Kurtural, Andrew E. Beebe, Johann Martínez-Lüscher, Shijian Zhuang, Karl T. Lund, Glenn McGourty, and Larry J. Bettiga

rising cost of labor presents an economic risk for SJV vineyards ( Kurtural et al., 2012 ). The average net return for wine grapes in central SJV is $327/ton ( CDFA, 2013 ). The low net returns, coupled with rising labor costs and seasonal droughts, have

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Alison L. Reeve, Patricia A. Skinkis, Amanda J. Vance, Katherine R. McLaughlin, Elizabeth Tomasino, Jungmin Lee, and Julie M. Tarara

:Y because leaf area is generally correlated with pruning weight. In practice, the objective is to optimize the source to sink ratio with vineyard management practices to sustain vine productivity and achieve ripeness within climatic constraints. Some studies

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Justine E. Vanden Heuvel, Steven D. Lerch, Celine Coquard Lenerz, James M. Meyers, and Anna Katharine Mansfield

preference for ‘Noiret’ wines produced from a young vineyard. Materials and methods Vineyard site and experimental design. The planting was established at the New York State Agricultural Experiment Station in Geneva, NY, in 2007 with dormant 1-year-old vines

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Thomas J. Zabadal, Gary R. VanEe, Thomas W. Dittmer, and Richard L. Ledebuhr

Functional leaf area is the basis for vineyard productivity. Therefore, the leaf area displayed on a trellis will determine the productive potential of a vineyard. A device that uses a series of infrared sensors was constructed to quantify vineyard trellis fill. A vertical row of sensors on a moving over-the-row vineyard trailer recorded the interception of infrared light beams through the trellis. These values were related to the total time of measurement to calculate a percentage of trellis fill. Our device was used to quantify differences among training systems applied to `Chardonnay' grapevines. This system is quick, easy, and at least as accurate as currently used visual methods. This technique should be useful for determining the influence of various cultural practices on the development of grapevine canopies.

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Mercy A. Neumann, Robert L. Wample, Julie Tarara, and Stephanie Greene

The location of the Columbia and Yakima valleys present vineyard managers in eastern Washington with significant concerns, particularly low rainfall and wind erosion. Cover crops, as part of a complete management system, can reduce the effects of wind erosion in vineyards by stabilizing soil particles and reducing runoff. Cover crops also reduce weed biomass. During research conducted at Prosser, Wash., 175 foreign and domestic species were assessed for performance as cover crops. Using a screening process, nine species were chosen for evaluation in large commercial plots. Grass species included cereal rye, crested wheatgrass, Sherman Big Blue wheatgrass, perennial rye, pubescent wheatgrass, and three fescues. Legume species included two annual clovers (Trifolium spp.) and two reseeding annual medics (Medicago spp.). Unseeded, resident vegetation served as a control. Vine and soil water statuses were monitored regularly. Initial establishment of all species was delayed because of low rainfall throughout the growing season; thus performance varied for each species. Drought-tolerant grass species had better germination and establishment than legumes, due to planting method. In-row water status and vine water potentials remained constant throughout the main portion of the growing season. A mix of crested wheatgrass, perennial rye, and pubescent wheatgrass (Canada mix) gave especially good cover without affecting vine or soil water status. Weed biomass was reduced in most cases, with legumes having least effect; cereal rye, crested wheatgrass and the Canada mix had the greatest effect. Season-long suppression was best achieved with the Canada mix because of the nature of establishment. In this study, most drought-tolerant grasses performed better than legumes; however, with proper establishment, legumes can be a beneficial part of a sustainable agriculture system.

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R. Paul Schreiner, Carolyn F. Scagel, and John Baham

The nutrient uptake and distribution patterns for N, P, K, Ca, and Mg were determined in mature (23 to 24 year old), field-grown, rainfed grapevines (Vitis vinifera L. `Pinot noir') growing in a red hill soil in Oregon in 2001 and 2002. Biomass, nutrient concentrations, and nutrient contents of all plant organs, including roots, were determined on 14 sampling dates over 2 years. There was no seasonal change in the standing biomass of primary roots (fine feeder roots), small woody (<4 mm diameter) or large woody (>4 mm diameter) roots. Trunk biomass also did not change during the 2 years, but all other vine organs showed significant seasonal changes in biomass. The rate of N uptake was greatest at bloom, when remobilization from reserves was also high. Nitrogen was also taken up after leaf fall in 2001, but not in 2002, when an early frost occurred before soil moisture recovery by fall rains. Uptake of N, K, and Ca from soil was similar between years, even though canopy demand for N and K was greater in 2002 (significantly larger crop). Phosphorus uptake from soil was lower in 2002 than in 2001, which was most likely due to the drier conditions in 2002. A greater quantity of canopy N, K, and especially P was supplied from stored reserves in the drier 2002 growing season. About 50% of canopy requirements for N and P were remobilized from reserves in the trunk and roots by the time of fruit maturity in 2002. Only 15% of canopy K and <5% of canopy Ca or Mg came from stored reserves in 2002. Our findings indicate that nonirrigated grapevines grown in Oregon acquire nutrients from soil earlier in the growing season and have a greater reliance on stored reserves of N and P than reported in previous studies from other growing regions. Replenishment of nutrient reserves occurred to large extent during the postharvest period. Rainfed vineyards in Oregon may require different nutrient management practices than irrigated vineyards, since low soil moisture may limit summer uptake of P.