What can I say besides boy is it hot! After no rain in May, plenty of rain in June and now over a week in the 90's everyone is steaming in the vineyard. The plants don't mind because most vineyards have irrigation or are old vines with extensive root systems. Actually, the heat will do the vines some good after such a cool spring. It is hard to stay motivated out there. Even the cover crops are starting to take a hit. Here are a few shots of clover under the trellis down at Channing Daughters Winery. These photos were taken on July 12th just before we moved into our second week of a heat wave.

The clover seems to be holding up well. This is the second season at this site and it came back nicely this year. Weeds are not as much of a problem in this trial but there is some mugwort that may be hard to control since it isn't being mowed.

Our summer intern, Matt Gura, will be posting a series of interviews he is conducting with the growers that are participating in the under trellis cover crop study. Here is his first interview with Jim Thompson, vineyard manager at Martha Clara Vineyards.

Greetings!

I recently had the pleasure of meeting with Jim Thompson to discuss his experiences with under-vine cover crops.  Jim manages Martha Clara Vineyards, where the CCE-SC grape program has the replicated trial evaluating under trellis cover crops.

Prompted by observing practices in the western US and Europe, Jim has been interested in alley and under-vine cover crops for many years.  The exposure led him to critically reflect on the impact of conventional practices involving herbicide use: “As it became more obvious that herbicides were going to become an issue for growers, like leaching, disruption of the dynamics of the ecosystem on the vineyard floor…and it became more popular to think about these issues, I felt that [covercrops] just made sense.”

When Jim was confident that the vines where he observed various cover cropping techniques did thrive, he recognized the relevance such strategies could have in his own vineyard:  “[My] vines are crazy vigorous, and in a region where some years you can get 10 inches of rain in June, what better way to soak up some of that water than these cover crops.”

                Jim has experimented with wall to wall cover crops in years past, but he primarily maintains an herbicide strip under the vine.  As he continuously follows under-vine cover crop research, I asked him if he considered the results positive such that he may be ready to adopt the practice: “Encouraging, but not positive.  We haven’t hit it yet as far as I’m concerned.”  As to what particularly concerns him, Jim replied: “Simply the management of them.  As they get too tall and get too close to the bottom of the vines, an issue is moisture retained by those groundcovers that transpires into the canopy.  If the soil is bare, then that would never happen.  There’s more to think about.”

Interview by Matt Gura, CCE-SC intern

                                    No mow only treatment at Martha Clara on July 9th.

We spent yesterday with Cornell University Professor Justine Vanden Heuvel touring our under trellis cover projects. She has similar projects going on in the Finger Lakes but is focusing her research on annual cover crops as opposed to perennial ones like we have in our trials. She brought her two grad students that are working on these projects. Here is a photo of the whole group over at Old Field.

We also stopped at Martha Clara, Mattebella and One Woman to see how the various trials are progressing. It is always nice to get different perspectives and share ideas on topics that are new and constantly evolving. One of the things we discussed was even though they are seeing differences in nitrogen levels from petiole samples there are not significant difference in vine growth between treatments or fruit parameters at harvest. This may be because they are not using a permanent cover crop year round like we are. They need to hill up their vines to protect the graft union in the event of an extremely cold winter. They are tilling in their cover crop each fall which may be providing a boost of nitrogen. Will be interesting to see how their trials progress compared to ours. We'll keep you posted! 

The season is well under way and the project is keeping us busy. At the beginning of June two interns from Cornell University came down to help in our research vineyard as well as with the maintenance and data taking in the under trellising cover project. Matt Gura and Drew Harner will be helping us through August.

We added three more under trellis sites this summer. One at Palmer, Old Field and Duck Walk Vineyards. Palmer and Duck Walk seeded clover under the trellis and Old Field seeded a low growing fescue mix. We will also be adding a fourth site in the fall at Shinn Estate. We want to see how germination rate and establishment are influenced by a fall seeding. The thought is that establishment of ground covers will be better in the fall when it is cooler, weeds are not actively growing and there is typically more rainfall.

Duck Walk clover just germinating in the Chardonnay on the left and Palmer clover in Syrah on the right.

Quick shot prepping the site for seeding at Old Field. The grass has since germinated so I will have photos up soon of that. 

 

We also have several sites that have since expanded their plantings of under trellis cover this year so I will describe some of those situations in future blog posts.  

Lets talk lysimeters.

When developing this project we came across some research done by Cornell University Professor Dr. Ian Merwin and Dr. Warren Stiles and their work with groundcovers in orchards (Merwin and Stiles, Orchard Groundcover Management Impacts on Apple Tree Growth and Yield, and Nutrient Availability and Uptake J. Amer. Soc. Hort. Sci. 119:209-215 1994). They compared various conventional and alternative groundcover management systems including a "living mulch" of crown vetch, mowed sod, chemically growth regulated sod, preemergence herbicide, postemergence herbicide, hay-straw mulch and rototilling. What we are interested in from this study is in the mowed and growth regulated sod treatments extractable soil N was reduced compared to the other treatments. We want to see if this is replicated in our vineyard trials but we also want to see if our seeded clover is fixing and releasing a measurable amount of nitrogen (the timing of it and if it is being taken up by the vines, through petiole analysis). To do this we have installed lysimeters.

With the help of the CCE-SC Agricultural Stewardship technicians we installed 39 lysimeters (for each treatment and rep) in the vine row at both the LIHREC mowing trial and the seeded cover trial at Martha Clara. Lysimeters are a large volume sampler designed to be installed near the ground's surface. We purchased 48" length lysimeters, put them in approximately 42" in the ground and will collect groundwater samples that we can analyze for nitrogen.

We will extract water samples throughout the growing season in the hopes of getting a handle on how our treatments are impacting N movement through the soil.

Innovative Under Trellis Management in Wine Grapes

2012 Summary by Alice Wise

In the spring of 2012 the CCE-SC grape research program received a multi-year grant from the Northeastern Sustainable Agriculture Research and Education program (SARE). 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.

The first objective of the project is to document that more growers are adopting mowing and/or green covers under the trellis. This is an effort to reduce leachable nitrates, reduce or eliminate herbicides, and reduce canopy management inputs, saving vineyards money while maintaining or improving yield and quality. In 2012, five growers agreed to seed cover crops in their vineyards seeding a total of 17.25 acres. These plots 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.

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.

The second objective is to determine the impact of undervine mowing on vines. 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. It is located in a Merlot block at the LIHREC research vineyard in Riverhead, NY. There were no significant differences in shoot length (measured three times) or shoot diameter. Vine pruning weights have yet to be analyzed. 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 will be installed in the spring of 2013.

The third and final objective of this project is to evaluate the impact of seeded under vine cover crops. This trial involves four treatments: glyphosate only (2x); Dutch white clover; no mow fescue mix; and a combination of clover and no mow. This trial is located in a Syrah block in a commercial vineyard on Long Island. 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 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. 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 levels. 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 will also be installed in this experiment in spring 2013.

I have been on sort of a blog hiatus this winter. Not for any reason other than it has been a busy winter analyzing data. We have some information from our first season with this project. Go to our webpage at  http://ccesuffolk.org/grape-research/ and click on the report titled "Innovative Under Vine Management Strategies" to see the full report. I will post a somewhat abbreviated version on this blog.

We spent some time looking at pruning weights this winter to gauge impact of covers on vine growth. Here is a before and after shot of one of the Merlot vines pruned in the research vineyard.

We will have a little more help this summer with the addition of two full time Cornell students as well as a part time person. We also have four additional vineyards that have joined our original five to try out groundcovers in their vineyards. More to come on the new blocks as well as a few interviews with some of the growers who participated last year and their thoughts on the first year of this work.