Innovative undertrellis management for vineyards

Innovative undertrellis management for vineyards

Summary

This project is designed to explore the use of cover crops or mowing for management of the area under grapevines. The majority of eastern winegrape growers maintain this area with herbicides, considered to be the easiest and most cost effective strategy. Green growth under vines is often viewed as detrimental, competing with vines for water and nutrients. However, many growers endeavor to reduce pesticide use and are therefore seeking viable alternatives. Forty-six growers in eight states responded to a survey conducted last spring to document current practices and gauge interest. A webcast broadcast to fifty participants highlighted related work of two researchers and reiterated the benefits of cover crop strategies. Five growers agreed to implement demonstration plots in their vineyards in 2012. Data was collected season-long from two research trials. The season’s activities were documented in a blog. Both research trials were featured during a field day in September. Upcoming events include a meeting with cooperating growers and presentations to growers in January and April.

Objectives/Performance Targets

1. 15 growers adopt mowing and/or green covers under the trellis on a total of 400 acres, reducing leachable nitrate by ? 10%, reducing or eliminating herbicides, and reducing canopy management inputs, saving $210/acre while maintaining or improving yield and quality.

   The milestones relevant to this season are listed below. We met with the five grower advisors in April, 2012 to discuss project goals. Each agreed to seed under-vine covers in a portion of their vineyard, a total of 17.25 acres in 2012. In one vineyard, clover seeds did not germinate. Each vineyard was visited during the summer to gauge progress with the project. We are scheduled to meet with this group again this winter to review performance of covers.

   1. March-April, 2012: We polled 46 growers for current practices and interest in alternative strategies. Results were posted to the blog and were utilized by GA group for planning demonstration plots. Survey results Table 1.
   2. May 10, 2012: 50 growers attended a webcast with lectures on green covers and their impact on vine vigor and nitrogen leachate. Go to http://ccesuffolk.org/viticulture. The lectures may be accessed at the addresses listed in the current events section.
   3. Sept. 5, 2012 tours of field plots: 11 people attended a tour of the groundcover research plots at Martha Clara Vineyards while 18 people toured under-vine mowing plots at Long Island Horticultural Research and Extension Center.
   4. Jan. 2013: A.Wise is scheduled to speak at Viticulture Session of LI Agricultural Forum, Riverhead. An April, 2013 meeting is scheduled with presentations by Cornell viticulturist Dr. Justine Vanden Heuvel (under-vine cover project with annual species) and A.Wise (Long Island results) as well as a panel discussion with grower advisors.
   5. Winter 2013: A call for additional cooperators will be made at the LI Agricultural Forum, at the April meeting and via the Long Island vineyard manager list serv. Our goal is to engage 5 additional growers interested in implementing mowing/covers. They will be asked to submit a plan to the GA group for review.

Accomplishments/Milestones

Survey – We used Survey Monkey to poll 46 growers in eight states. We had hoped for more participation but regional growers were likely suffering from ‘survey fatigue’. The results reflect what we have heard from growers in discussions. They feel that herbicides are less costly than labor-intensive alternative strategies. They fear green growth under vines will reduce yield and quality. There was also concern about a reduction in vine size (viewed as a negative attribute) and potential rodent damage.

Webcast –120 people signed up, representing 21 states and five countries. Fifty actually viewed the webcast, five of those attending at LIHREC. Nine people asked about viewing the archived presentations. The presentations compared perennial and annual under-vine covers, the latter necessary in regions that have to hill up around the graft before winter. There was also a review of research results that indicated a reduction in leaching of nitrogen and pesticides where covers were maintained under vines. The webcasts can be viewed on our website – http://ccesuffolk.org/viticulture in the current events section.

Research trials – We maintained two research trials. An under-vine mowing trial is located in a Merlot block at the Long Island Horticultural Research and Extension Center. An under-vine cover crop trial is located in a commercial vineyard, cv. Syrah. We collected data from these blocks season long.

Field plots tour – Originally, we planned to host meetings at each cooperating grower vineyard. We decided to focus on field visits to the two established research trials in 2012 and the grower plots in subsequent years. Growers were most interested in the cost of materials, maintenance, cover crop species and contributions of clover to vine nitrogen status. We toured both trials with Napa Valley CE Weed Scientist John Roncaroni on July 5 and the Cornell University Viticulture class on October 3.

Blog – The blog was set up on March 1, 2012. There have been 13 posts with 432 page views. The blog is intended to provide project updates including photos. http://iutmforvineyards.blogspot.com/. We were not successful in getting growers to contribute. Next year, we plan to do interviews. Busy growers may not be motivated to post to a blog but would likely be happy to discuss their observations if we take care of the details.

• Grower survey

Impacts and Contributions/Outcomes

Grower advisor plots: Five growers agreed to seed cover crops in their vineyards. These included several types of clover and no mow fescue mix. In several cases, the expense of seed dictated the choice of cover. In one vineyard, clover plots did not germinate. Some growers were unwilling to host herbicide plots for comparison, understandable for those with a goal of avoiding herbicide use. There was some frustration with escape weeds getting up into the canopy as the fixed fruiting wire is only 28-36” high. It was necessary to address taller escape weeds at least once a season. In these trials, growers used a push mower (mowed high) or machetes. Other growers have used weed whackers. The thickness of the thatch in no mow plots reduced escape weeds but there is a big concern about rodent damage over the winter.

In three of four vineyards, there were visual differences in vine size and leaf color between groundcover treatments. In one vineyard, vines were noticeably larger in clover plots. In a second vineyard, vines with clover seeded in 2011 were much larger than vines with clover seeded in 2012. Fruit in these clover plots had lower sugar and higher acids at harvest, suggesting a delay in ripening. We have not yet taken pruning weights in the third vineyard. While the vine size difference was not surprising, we did not see this same result in our cover crop research study. Similarly, we have not found any differences in fruit ripening among treatments in our replicated cover crop study. Collection of data for a detailed cost analysis will begin this winter.

Under vine mowing trial summary: This trial involves four treatments: T.1 – season long mowing (5 times); T.2 – glyphosate only (3x); T.3- mowing (3x plus glyphosate early July); and T.4 – mowing (4x) plus glyphosate early August. There were no significant differences in shoot length (measured three times) or shoot diameter. We conducted a point quadrat analysis on August 9, an evaluation of canopy density. We will be analyzing the data this winter. Vine pruning weights will also be taken this winter. Vine nutrition, as determined through the analysis of leaf petioles, was similar for all treatments with the exception of phosphorus, which was lower in the glyphosate only plots. There were no differences in yield or fruit ripeness at harvest. We were hoping that the use of green cover (potential competition for water and nutrients) would reduce berry size (higher skin:flesh is desirable in reds for color and flavor compounds) but we have not been able to document this effect. Lysimeters to gauge nitrate leaching were not installed in 2012 due to budget constraints. The lysimeters and associated equipment will be installed in early spring 2013. Similarly, spring soil samples were not taken in 2012 but will be collected in 2013. Several tables are included with this report. Additional data will be posted this winter at our website http://ccesuffolk.org/viticulture.

Under vine cover crop trial summary: This trial involves four treatments: glyphosate only (2x); Dutch white clover; no mow fescue mix; and a combination of clover and no mow. By year two, the clover dominated the no mow. There were no significant differences in shoot length or in shoot diameter. The six central vines in each plot were pruned on December 6. Vines in no mow plots were visually smaller and though not statistically significant (p=0.0522). There may be differences next season if this trend continues. Pruning weights in the clover and herbicide plots were similar, unlike what was noted in several grower vineyards. We had expected the clover to stimulate shoot growth. We conducted a point quadrat analysis on August 9, an evaluation of canopy density. We will be analyzing the data this winter. In petiole analysis, though not statistically significant, there was a trend for lower petiole nitrogen in no mow plots. The two treatments with clover had significantly lower phosphorous. Phosphorous fertilization is often recommended when establishing clover for forage. Long Island soils however tend to be high in phosphorous due to a history of row crop vegetables prior to vineyard establishment. Lysimeters to gauge nitrate leaching were not installed in 2012 due to budget constraints. The lysimeters and associated equipment will be installed in early spring 2013. Similarly, spring soil samples were not taken in 2012 but will be collected in 2013. Several tables are included with this report. Additional data will be posted this winter at our website http://ccesuffolk.org/viticulture.

• Under vine cover crop trial
• Under vine cover crop trial
• Cooperating grower results
• Under vine mowing trial
• Under vine mowing trial

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