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Site Selection, Trunk Injury, and Sucker Management

Site selection and the freeze:  I had the chance to visit 8 vineyard sites in the Thousand Islands/Tug Hill region last week, and I was struck by the contrasting impact of the May 22-23 freeze. Simply put:  Hillsides with air drainage fared better. Three vineyard sites on hillsides have a normal crop.  The 5 vineyard sites I visited that were planted on flatter sites or at the bottom of slopes invariably saw serious injury (more on that below).   The NNY Grape Growers Association (at Tug Hill vineyards)  hosted a speaker from Shur-farms, talking about air drainage and the prospects of improving it.  The most important point, which I have seen validated not just in the 1000 Islands, but also in vineyards here in the Finger Lakes is this:  During radiation freezes where the air is still,  air flows downhill, just like water – and can form cold air lakes of varying depths.  Promoting airflow via removal of obstructions and proper placement of fans, can help remediate this issue.  But the best way to avoid spring frost injury is through site selection:  Air drainage is important!

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Marquette vineyard (hillside) near Clayton NY is bearing a full crop.

Winter Injury versus spring frost injury.  Many of the sites I saw had collapsing and dead trunks interspersed in the vineyard.  In all likelihood, this was the result of previous winter injury from last year (2013-2014 winter) or a combination of last winter plus this winter.  The May 23 frost, while it froze green shoots, was not severe enough in my opinion to compromise conductive tissue in the trunks (xylem and phloem).  Most sites are probably looking at trunks that have accumulated damage over the winter – or past two winters.   Following the 2004 winter injury episode in the Finger Lakes, we saw vines continuing to collapse over the next two growing seasons.

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Vineyard with dead canes, retained for training up suckers. August 29

Sucker Management and training new trunks.  I want to draw upon work done by Dr. Imed Dami (some of it on Marquette) in Ohio in 2014.  When confronted with trunk injury, the task is to train up new trunks (or a new trunk) to get the vine back in production.  Imed’s recommendations, based on field trials amount to the following:

1. Retain all the suckers during the growing season. Mature vines still have an intact root system, and by retaining them, you can avoid producing one or two large diameter ‘bull canes’.

2. Select medium (pencil-diameter) suckers to retain as trunks.  Bull wood is more subject to winter injury.  Imed found that large-diameter canes were as much as 8 degrees less cold-hardy than moderately sized canes.

3. Use ‘Active/Continuous Training’ if possible.  This is the novel part of the story.  In pictures:

A. Imed took some vines and either let them grow vertically, or trained them horizontally at the mid-wire. He found that training the shoots horizontally promoted growth of laterals, setting the vine up for a crop the next year (see photo below). It also devigorates the shoot somewhat.

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Minimum training versus active training, where replacement shoots are loosely wrapped aroung the mid-wire. Photos courtesy Imed Dami, Ohio State University.

B. Those that weren’t ‘actively trained’ tended to grow excessively.

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Photo by Imed Dami, Ohio State University, Wooster OH

 

C. Actively-trained vines had their foliage more evenly deployed to fill up the trellis space, and set the vines up for production in the following year.

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Photo by Imed Dami, Ohio State University, Wooster OH

The upshot:  By managing suckers following trunk injury, growers may be able to bring vineyards back into production earlier, and have a more manageable time pruning and training vines next year.   My thoughts are that if growers are using a high cordon, it still might be easier and more productive in the long run to first train suckers out the middle wire, and bring them up to the high wire in a two year process.  Remember: when you are training green shoots, wrap and tie loosely to avoid girdling shoots.  Its worth a try on at least some of your vines.  Chrislyn Particka and I are going to try it out on a selection of vines this year.  Should be done as soon as possible, you will see little benefit past August 1st.

Thanks to Imed Dami, associate professor at Ohio State University’s OARDC in Wooster OH,  for sharing his powerpoint presentation with me, and allowing me to use portions in this post. These photos were part of a presentation entitled “The 2014 Polar Vortex: Research Findings and Lessons Learned”, presented at the Eastern Winery Exhibition in Syracuse, NY.

 

 

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