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.

Last friday we picked syrah at Martha Clara. Just to refresh your memories - at Martha Clara Vineyards we have a trial with 4 treatments: glyphosate only, seeded clover only, a low growing mix of fescues called "no mow" and a mix of clover and no mow. The three vegetative treatments were seeded directly under the vine row in the spring of 2011. The idea behind these treatments is that growers are looking for a way to eliminate herbicide but not have to mow either. Throughout 2011 and 2012 we have been taking data on vine growth to determine if these under trellis covers will impact vine health. At harvest last week we were able to take data on the crop from the 2012 season. The week before we had taken 100 berry samples to measure berry weights, total acidity, brix and pH. These are basic parameters to help gauge ripeness of fruit. We then picked each vine individually, counting the number of clusters and weighing them, to determine crop weights in the different treatments. Finally, we counted berries on 10 clusters from each treatment and rep. This is to determine differences in fruit set.

Here is a picture of the crew counting berries after harvesting the trial.

I also took some shots of the cover crops. This shows the height of the clover and no mow in the fall. The clover had died back a little bit in the heat of the summer. The vines were irrigated once. Part of each treatment was mowed this fall. As the row middles were mowed they did come into the vine row a bit on each side.  Where we had a 2 ft area of cover crop, a half a foot was mowed on either side - giving the treatments the appearance of a mohawk. But it grew back quickly.

Here are the vines after picking.

In the next couple weeks we will be picking the Merlot trial at the research vineyard. Then we will start the process all over again with pruning over the winter.

The fruit from our trials as well as from the grower plots are slowly being picked. The whites from One Woman and Channing Daughters have come in and the reds from Martha Clara, Bedell and here at the research vineyard will be coming in soon. Here are a couple photos of the Gruner Veltliner from One Woman Vineyards.

It is almost time for harvest - can't believe another season is almost over. I wanted to mention a few things that happened in July and August that didn't make it in their own blog post.

Back in July Napa County UCCE Weed Science Advisor John Roncoroni visited Long Island. His specialty is in weed control and vegetation management for perennial crops, cover crops and aquatic and riparian weed control. We took him to see both trials in this project, the under trellis mowing at LIHREC and the under trellis cover crops at Martha Clara. We also took him out to Bedell where they had planted no mow and red clover. Interestingly he mentioned that in his experience with no mow it isn't a completely no mow situation. It can get up to 16 in high (when it is flowering) so would benefit from a single mowing in the fall. He also felt that even without mowing or incorporation, the clover may add some nitrogen to the soil. Hopefully we will see this is our soil and petiole test results. Last year we mowed the trial at Martha Clara in an attempt to knock back the weeds and allow the cover crop to becom established. This year we will mow and not mow a few replications of each treatment to see the different growth patterns of our cover crops.

John Roncoroni (on the left) and Andy Senesac, Suffolk County Cornell Cooperative Extension weed specialist.

In August we took more data from the two trials. We took petiole samples at veraison to give us a snapshot of the nutritional status of the vines going into harvest. Petioles combined with soil samples will allow us to see if the cover crops are having an impact on the nutrional needs of the plant. It is thought that plants grown under the vine will compete with the vine for nutrients and impact the overall health of the vine. In Martha Clara where vigor is an issue this might not be such a bad thing, but at LIHREC where vigor is not as much of an issue it could be a problem.

                                             Petioles from LIHREC

Also at veraison we took samples of the cover crops, dried and weighed them. This will give us a better idea on their growth over time. The potential problem is that the weeds will start to move in and crowd out the planted covers. Or they don't reseed themselves and start to die out. This gives us an opportunity to better track this.

Clover, before and after sampling. All of the vegetation in the 12 in x 12 in square was harvested. Weeds were removed before I put them in the drying oven. We can use this small sample to extrapolate to the entire plot.

                                                      No mow samples