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eViticulture

2005 Best Management Practices Report

Demonstration and Verification of Best Management Practices for Winegrape Production in the Ozark Mountain Region

Viticulture Consortium, East 2005 Progress Report

Principal Investigators:

Andy Allen, Viticulture Adviser
Mid-America Viticulture and Enology Center, Missouri State University
9740 Red Spring Road, Mountain Grove, MO 65711
Phone: 417-547-7508
Fax: 417-547-7536
E-mail: raa898t@missouristate.edu
20 percent time

Keith Striegler, Assistant Director – Viticulture
Mid-America Viticulture and Enology Center, Missouri State University
9740 Red Spring Road, Mountain Grove, MO 65711
Phone: 417-547-7566
Fax: 417-547-7536
E-mail: rks464f@missouristate.edu
10 percent time

Cooperators:

Donn Johnson, Professor
AGRI 320, Department of Entomology
University of Arkansas
Fayetteville, AR 72701
Phone: 479-575-2501
Fax: 479-575-2452
E-mail: dtjohnso@uark.edu
10 percent time

Laszlo Kovacs, Associate Research Professor, Plant Pathologist
State Fruit Experiment Station
Missouri State University
9740 Red Spring Road, Mountain Grove, MO 65711
Phone: 417-547-7524
Fax: 417-547-7540
E-mail: lgk378f@missouristate.edu
2 percent time

Wenping Qiu, Assistant Research Professor, Virologist
State Fruit Experiment Station
Missouri State University
9740 Red Spring Road, Mountain Grove, MO 65711
Phone: 417-547-7517
Fax: 417-547-7540
E-mail: weg070f@missouristate.edu
2 percent time

Objectives

  1. To conduct surveys to establish a benchmark and quantify progress in adopting grape best management practices and to identify constraints to implementation in Arkansas and Missouri.
  2. To demonstrate grape best management practices.
  3. To disseminate information about grape management, and pest and disease events in a timely manner.
  4. To produce a Wine Grape Integrated Production Systems Workbook for use in grower grape best management practices workshops.

Summary of Major Accomplishments and Results

Objective 1: To conduct surveys to establish a benchmark and quantify progress in adopting grape best management practices and to identify constraints to implementation in Arkansas and Missouri.

  • A survey form regarding current grapevine canopy, insect, and disease management practices was compiled and sent to growers in Arkansas and Missouri in November 2005. Currently, we are compiling the information from the surveys and following up by contacting non-respondents by phone to encourage submission of the completed survey form and to clarify responses from others.

Objective 2: To demonstrate grape best management practices.

  • Cooperating vineyards were identified in six locations representing the major winegrape production areas in Arkansas and Missouri. These locations were Altus and Hindsville, Ark., and Ste. Genevieve, St. James, Hermann/Augusta and Rocheport, Mo.

    Demonstration blocks were established by Keith Striegler and Andy Allen at each of the six cooperating vineyard sites in April. In each of these blocks, selected canopy and crop load management practices were performed, depending on the variety and trellis system.

    At Altus, Ark., the vineyard block was Merlot trained to a Vertical Shoot Positioned (VSP) trellis and the management practices used were shoot thinning, leaf removal within the fruiting zone, cluster thinning and all treatment combinations.

    At Hindsville, Ark., the vineyard block was Chambourcin trained to a high-wire, single-curtain trellis, and the management practices were shoot thinning, shoot positioning, leaf removal, cluster thinning and all treatment combinations.

    At Ste. Genevieve, Mo., a block of Chardonel trained to VSP was used and the practices were the same as those at Altus.

    At St. James, Mo., the block was Chardonel trained to a high-wire, single-curtain trellis system, and the management practices included shoot thinning, shoot positioning, cluster thinning and all treatment combinations.

    At Rocheport, Mo., the block was Vignoles trained to a high-wire single-curtain trellis system, and the practices included shoot thinning, shoot positioning, leaf removal, and all treatment combinations.

    At Hermann, Mo., a block of Vignoles trained to a high-wire, single-curtain trellis was used. The treatments in this case were designed to reduce cluster susceptibility to bunch rot by altering the very tight cluster architecture of Vignoles, which is highly susceptible to bunch rot.

    Treatments in this block included brushing of the clusters to remove individual florets, removing the basal 6 to 8 leaves from fruiting shoots at trace bloom, Stylet oil application at trace bloom (not performed in 2005), and an untreated control. These demonstration blocks, with the exception of the Ste. Genevieve Chardonel block, were harvested the day before the growers harvested the entire variety block.

    The Chardonel demonstration block at Ste. Genevieve was not harvested due to poor vine growth. This block will be moved to a more vigorous area of the vineyard in 2006. Yield, cluster counts, and where appropriate, bunch rot incidence data were collected. Also, berry samples for average berry size and fruit composition analysis were collected. Additional variables were calculated from these data.

    In the Altus, Ark., Merlot block, the canopy and crop load management practices had no significant effect on any of the variables measured. This result was likely influenced by several factors. First, vines were not irrigated in this vineyard block during the 2005 season resulting in periods of severe water deficit. Secondly, the hot, dry conditions of the 2005 season favored severe powdery mildew pressure, which was evident in the block.

    Although not statistically significant, the leaf removal treatment combined with shoot thinning tended to reduce the incidence of powdery mildew.

    In the St. James, Mo., Chardonel block, the treatments also had no significant effect on any of the variables measured. In this case, the vines were young with open canopies and were lightly cropped.

    In the Hindsville, Ark., Chambourcin block, crop load management (cluster thinning) significantly reduced cluster numbers and yield per vine, but tended to increase the number of berries per cluster and average cluster weight compared to other treatments. It also significantly increased the percent soluble solids and pH compared to other treatments.

    Canopy management treatments had less effect, probably due to drought-induced defoliation in the fruiting zone approximately one month prior to harvest. Although this vineyard was irrigated, the water source (pond) ran dry in late summer.

    At the Rocheport, Mo., Vignoles block, the number of berries per cluster and average cluster weight were significantly increased by shoot thinning . Other canopy management practices had inconsistent and insignificant effects on all variables measured, probably due to a trellis system failure that allowed vine canopies to roll.

    At the Hermann, Mo., Vignoles block, the leaf removal at trace bloom treatment significantly reduced cluster weight and number, and, therefore, yield per vine. It also significantly reduced the number of berries per centimeter of rachis length, resulting in looser clusters, which drastically reduced the percent of clusters infected with bunch rot, although the effect was not statistically significant. Berries from the leaf removal treatment also had higher soluble solids and pH and lower titratable acidity, indicating a higher level of maturity.

    Half-day field workshops were held in May, June and July at the six demonstration vineyard sites. The sites with their attendance (in parentheses) were:

    • Arkansas: Altus (10 growers) and Hindsville (9)
    • Missouri: Ste. Genevieve (30 growers), St. James (15), Hermann (20) and Rocheport (25)

    During these workshops, Keith Striegler, Andy Allen, Donn Johnson and Barbara Lewis talked to more than 100 growers and extension personnel. The best winegrape management practices topics covered included:

    • Demonstration of canopy and crop load management practices including shoot thinning, shoot positioning, leaf thinning and cluster thinning.
    • Petiole and soil sampling for vineyard nutrient management.
    • Irrigation management.
    • Weed management.
    • Pesticide use and pre-harvest intervals.
    • Demonstration of grape pest scouting and decision-making pest management program for grape berry moth, grape phylloxera, grape root borer, grape scale, Japanese beetle and green June beetle.

    Growers in these six demonstration vineyards in Missouri and Arkansas were shown when and where to set out pheromone traps for grape berry moth (at edge of woods by vineyard by April 1 and move to vineyard center in mid May). These growers or a scout, already under their employ, kept weekly insect trap count records for Missouri vineyards and Arkansas vineyards. Trap data were conveyed weekly to Donn Johnson by phone or e-mail and uploaded into a table of trap catch on two Internet pages:

    In Missouri, the GBM trap counts were high for the first generation from April 1 to June 10. Trap catch for the later generations remained below 10.5 moths per trap per week in all vineyards except the St. James shed block. Season total trap catches for the Missouri vineyards in ascending order were: Crown Valley (27), Les Bourgeois (88), Stone Hill (129), St. James tower (150) and St. James shed (402).

    The first flight of GBM began by April 5, peaked in Missouri at 37 GBM per trap on April 15 at Les Bourgeois (Rocheport) and on April 21 at Crown Valley (Ste. Genevieve = 6.7), Stone Hill (Hermann = 19,7) and St. James (123) vineyards compared to a peak on April 22 of 36.5 GBM / trap in Hindsville, Ark.

    The season total GBM trap catches for Arkansas were: Altus (169), Hindsville low risk (177) and Hindsville high risk (279). The first generation GBM trap counts were low in the Altus block and the low-risk Hindsville block (surrounded by open fields) but high in the Hindsville high-risk block where 40 percent of the perimeter was adjacent to woods.

    The May removal of clusters from young vines (third leaf) in the northern eight rows nearest the woods and insecticide sprays applied to the border of this high-risk block in Hindsville resulted in low GBM trap catch and cluster damage. However, high trap counts occurred in August (68 GBM caught) in the high-risk block in Hindsville of high-value 'Chambourcin' grapes justifying another full vineyard insecticide spray.

    A spray was recommended in the low-risk Hindsville block (93 GBM caught) of lower-value 'Concord' grapes but none was applied because of the already high irrigation costs due to drought from early July to September. The block in Altus experienced a gradual increase in trap catch from early June (second generation) to late-July (160 GBM caught) although cluster damage remained less than one percent.

    At field workshops in June and July, growers were shown how to make cluster damage estimates by inspecting 300 clusters for worm damage during each generation of grape berry moth. The recommended economic threshold was to apply insecticide only to the vineyard edge vines for first generation in May and early June and the whole vineyard for later generations only if more than one percent of clusters had new worm damage.

    In 2005, Donn Johnson and Barbara Lewis gained experience using a Spectrum™ WatchDog weather station (Spectrum Technologies, Inc., 12360 South Industrial Dr., East Plainfield, IL 60585; 800-248-8873) that was available from a previous project and placed at the Hindsville, Ark., site. WatchDog weather stations were unable to be purchased for all of the locations in 2005 due to funding not being received until after the growing season was finished; however, they will be purchased and installed at each of the six demonstration vineyard locations this winter.

    In December 2005 workshops, growers were shown the Hindsville, Ark., weather station data, actual fungicide usage for that vineyard and how these compare to the predicted infection periods noted by disease risk models for black rot, powdery mildew, downy mildew and botrytis diseases.

    From May 4 to harvest, a WatchDog weather station logged data every half hour: air temperature, minutes of leaf wetness, %RH and inches rainfall in the vineyard in Hindsville, Ark.. These data were downloaded weekly either to a WatchDog™ Shuttle or directly to a laptop computer using Spec7 Pro™ software.

    Temperature and hours of leaf wetness data were used to run the Spec7 Pro™ software prediction models for grape black rot and botrytis and downy mildew and powdery mildew. Steve Bost, Ph.D., (plant pathologist at the University of Tennessee) and Turner Sutton, Ph.D., (plant pathologist at North Carolina State University) are assisting to interpret these model outputs and prepare a protocol to validate these disease models during the 2006 growing season. It is hoped that some of the breakdowns in disease control observed this season will be explained by reviewing fungicide spray records for 2005 versus hours of leaf wetness and temperature and rainfall data nearest each vineyard.

Objective 3: To disseminate information about grape management, and pest and disease events in a timely manner.

  • Information on key insect pests and diseases was collected during the 2005 season. This information, as well as recommendations for canopy management and other viticultural practices, was provided to growers electronically (Web site) and face-to-face at vineyard workshops. A summary of insect pest and disease information follows:

    • Grape Berry Moth (GBM) is the key insect pest of wine grapes in the Ozark region. County and regional zone temperature data for Arkansas and Missouri from the extension services were used to derive cumulative degree-days (DD, base 47.14В°F, Tobin et al. 2001).

      Predicted periods of GBM larval attack of clusters for each generation in Northwest Arkansas were from: May 4 to 27 (perimeter vines), June 9 to July 3 (GBM attacking further into vineyard) and July 9 to harvest (generations overlap and attack whole vineyard).

      Similarly, each GBM generation occurred in Missouri in: Cape Girardeau Co. from May 6 to 26, June 6 to July 2, and July 19 to harvest; Crawford Co. from May 11 to June 5, June 23 to July 12, and July 24 to harvest and in Boone Co. from May 16 to June 8, June 24 to July 14, and July 26 to harvest.

      The number of insecticide sprays applied per season against GBM varied by vineyard: growers applied six sprays in Hindsville and five in Altus, Ark.; and four sprays in Rocheport, four in Hermann, four in St. James and 11 in Ste. Genevieve (Table 7). GBM damage in all six demonstration vineyards was kept to < 1 percent fruit cluster damage by harvest.

    • Japanese Beetles (JB) were first reported in St. Louis, Mo., in 1936 and in Northwest Arkansas in 1998. To date, this pest has caused minimal damage in vineyards along the Mississippi River from Augusta to Ste. Genevieve, Mo.

      However, it reached pest status in 2001 in Lowell and Springdale, Ark. That year, growers applied four to seven weekly insecticide sprays from July 2 to August 21 to prevent grape foliage damage by JB adults.

      In 2005, the Lowell grower reported a lower JB population, but still applied seven sprays at half the recommended rate to the top one-third of the canopy. In contrast, vineyards in Springdale and Hindsville, Ark., had economically damaging populations of JB only from July 8 to August 8.

      The Hindsville grower reported applying insecticide on June 21 and 25, July 6 and 14.

      In 2005, a season-long survey was conducted at each demonstration vineyard and several other sites to assess presence and abundance of JB. The first sighting of adult JB occurred in Northwest Arkansas on June 1. That week, one JB Jumbo trap baited with a floral lure and a sex pheromone lure was placed in each of six vineyards in Missouri (Hermann, Mountain Grove, Purdy, Rocheport, Ste. Genevieve and St. James) and seven sites in Arkansas (Altus, Berryville, Elkins, two sites in Fayetteville, Hindsville and Springdale) (Lures from: TrР№cР№ Inc., Adair, Okla; traps from: Great Lakes IPM, Inc., 10220 Church Road, Vestaburg, MI 48891-9746; Toll Free: 1-800-235-0285).

      The JB traps in Missouri captured: 4,051 JB in Crown Valley Winery (Ste. Genevieve); 13 JB in Purdy; 4 JB in Les Bourgeois Winery (Rocheport); and 0 JB in Stone Hill Winery (Hermann), St. James Winery (St. James) and Mt. Grove vineyards. The JB captured in traps in Arkansas totaled: 89,693 JB in Elkins; 86,373 in Springdale; 71,228 on the University of Arkansas-Farm in Fayetteville; 62,945 west of Sang Avenue in Fayetteville; 33,129 in Hindsville; 55 in Berryville; and 0 in Altus. Insecticide sprays were only applied against Japanese beetles in the Springdale and Hindsville vineyards.

    • Green June Beetle (GJB) populations exceeded economic threshold in Altus and Hindsville, Ark., from mid-July to August 20. Insecticide sprays were applied to prevent fruit damage in Altus on July 26, August 3, 8 and 20 and in Hindsville on July 19. No GJBs were observed in the four Missouri vineyards.

    • Grape Root Borers (GRB) were first sighted on July 16 in Ste. Genevieve, Mo. That week, one GRB sex pheromone trap was set out in each demonstration vineyard in Missouri (Hermann, Rocheport, Ste. Genevieve and St. James) and two demonstration vineyards in Arkansas (Altus and Hindsville).

      Growers were also shown how to sample 100 vines per vineyard for GRB pupal skins on the soil surface under vines. In 2005, the number of GRB moth per trap (in parentheses) were extremely low in all vineyards in Missouri: Rocheport (0), St. James (8), Hermann (11) and Ste. Genevieve (31) and in Arkansas: Altus (4) and Hindsville (9).

      In early September, 100 vines in each demonstration vineyard were inspected for GRB pupal skins. There were only two pupal skins found in the Ste. Genevieve vineyard and none found in the other five vineyards. No insecticide sprays were applied against this insect species.

    • Grape Phylloxera (GP) were observed in most demonstration vineyards. However, the GP insecticide, endosulfan, was applied only to the 'Chambourcin' vines in Hindsville, Ark., on June 13 and 21. The other vineyards in this project had vines with leaf galling caused by GP but no reports of insecticide.

      It is apparent that more research is needed on GP in the Ozark region. Therefore, a two-year grant proposal is being submitted to the Missouri Grape and Wine Board Research Committee and the Viticulture Consortium East that has three objectives:

      1. To survey and rank foliar and root grape phylloxera infestations on the major winegrape cultivars growing in the Ozark Mountain Region self-rooted and on grafted rootstocks as in Striegler's rootstock evaluation trials.
      2. To compare and demonstrate spray and timing effectiveness of Thiodan against grape phylloxera to that by new formulations of Assail®, Admire Pro® and Danitol®.
      3. To quantify the impact of phylloxera leaf galling and root damage on grapevine performance (yield, juice quality, pruning weight and winter injury).
    • Disease management in terms of fungicide formulations varied among the growers in Missouri. In Missouri, growers applied an average of 27.4 fungicide sprays per season (many as tank mixes) to the St. James tower (36) and shed (25) vineyards, Stone Hill vineyard (27), Crown Valley vineyard (37), and Les Bourgeois vineyard (12).

      The formulations used are ranked by average number of sprays applied per vineyard (in parentheses): Captan or Captec (5.8), Dithane (5), Sulfur (4), Nova (2.2), Abound® (1.6), Cu SO4 (1.2), Rubigan® (1.2), Iprodine (1), Penncozeb® (1), Bayleton (0.8), Elevate (0.8), Vanguard (0.6), Phostrol (0.4), Pristine (0.4), Sovran (0.4), Rovral (0.2), Thionex (0.2), Elite (0.2), FeSO4 (0.2) and Ziram (0.2). There were ten fungicide sprays applied in the Hindsville, Ark., vineyard.

      At field workshops, growers were trained to make decisions about managing grape insect pests by monitoring pheromone trap catches for GBM, GRB, JB and GP. Tables of pest trap counts were updated weekly or as data were received from growers or scouts and available on the Internet at:

      Temperature and rainfall (daily and cumulative) data were downloaded for each of the four vineyards in Missouri from the University of Missouri Extension. Hobo temperature loggers were in each vineyard in Missouri and Altus, Ark., to allow for an end-of-season comparison of in-vineyard Hobo temperature data to that of the nearest county or region temperature data provided by extension.

      The regional temperature data for Clarksville, Ark., that was used for the Altus vineyard site (10 miles apart) came from the Arkansas Cooperative Extension Service.

      Graphs of cumulative daily DD for GBM were available for all six vineyards on the Internet. Arkansas data was used to generate graphs of cumulative DD for GBM development.

      Missouri data was used to generate graphs of cumulative DD for GBM development.

    Objective 4: To produce a Wine Grape Integrated Production Systems Workbook for use in grower grape best management practices workshops.

    • A meeting of the principle participants in this project was held in September to discuss subject matter and format for the workbook. This workbook will be composed during the winter of 2005 to 2006.

    Dissemination Activities

    Dissemination of information is a key objective of this project and in 2005 was accomplished through the use of a Web site and the vineyard field workshops in May, June and July. A season wrap-up meeting was held in December 2005 at each of the locations at which the results from the canopy management blocks, trap counts, and pesticide use at each location were discussed.

    In addition, the following dissemination activities have been carried out: Striegler, Keith. Balancing Crop Loads for Quality in the Ozark Mountain Region. Presentation to the Texas Wine and Grape Growers Association Grape Camp Meeting. Nov. 12, 2005.

    Detailed data may be obtained by contacting:

    MaryLou Dumbleton
    Jordan Hall
    NYSAES/Cornell University
    Geneva, NY 14456
    Phone: 315-787-2290
    Fax: 315-787-2276

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