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Veraison in Marquette: Top Wire vs Vertical Shoot Positioning

by Tim Martinson

Justine Vanden Heuvel and I visited our Marquette and Frontenac training trials last thursday (July 31), and noted that veraison is starting on Marquette.

1. Top Wire Cordon:  Many of the high-trained clusters (Top Wire Cordon and Umbrella Kniffen) were just starting to turn.

IMG_7279 Veraison 2014

 

 

 

 

 

2.  Top Wire versus VSP.  In contrast to the TWC vines,  clusters on the midwire-trained VSP (Vertical Shoot Positioning) vines were smaller,  fewer, and have not started veraison yet.  In the photo below, TWC is on the left and VSP is on the right side.

IMG_7299

Comments

6 Responses to “ Veraison in Marquette: Top Wire vs Vertical Shoot Positioning ”

  • John Marshall

    Have the two trellis systems been hedged at this point?

  • tem2@cornell.edu

    Hi John, The VSP has been hedged. We don’t hedge the Top Wire Cordon, but rather just do downward ‘shoot combing’.

  • John Marshall

    When was the VSP hedged? I have found that the fruit of the VSP, if not hedged early enough become deeply shaded and thus do not color as early as the HWT as you are finding. Moreover, the smaller clusters and less fruitful buds on the Midwire trellis is consistent with buds that developed in partial or complete shade (in years past)making this system appear to be less productive than the HWT and that ultimately ripening will, no doubt, be less complete as well
    My own experience suggests that timely hedging is critical to complete ripening wih VSP (more properly Mid-wire) and to maintain fruiting capacity. Your photo simply shows someone holding a green cluster beside a partially colored one. It would be far more instructional to show each trellis system from which this experience is taken and the positioning of the clusters as regards sun exposure and comparative coloring in this backdrop.
    My own experience with comparative ripening of VSP and HWT (with Frontenac)showed higher sugars and slightly lower acids with VSP every year except one, we did comparisons until we concluded that for Frontenac (if hedging was done early enough and carfully,sun exposure and ripening was always better. As wineries become more experienced and fussy an improvement in ripening will become critical in selling grapes.
    Moreover, with HWT sun exposure normaly was only on one side of exposed fruit whereas VSP hung below the fruiting wire and got light from both sides. We believe this is especially critical when growing Lacrescent as the shaded side stays green and does not turn golden or yellow and reportedly does not produce the same wine.
    The HWT is great for drooping vines of Labrusca parentage and is very low in maintainance whereas VSP is much higher in cultural maintainance but gives better ripening to upward growing vines if it is hedged early enough and the fruit hangs in sunlight below the fruiting wire.
    That is my experience and I am glad to share it.
    John

  • tem2@cornell.edu

    Hi John – Thanks for the comment.
    We first hedged when shoot tips were about a foot above the top wire. (late June, around fruit set). We also did early shoot thinning to about 5 per ft on all systems. Early hedging has its drawbacks – notably promoting lateral shoot growth around the clusters. We also have done early basal leaf removal, so clusters were pretty well exposed.

    Here’s our write up of last year’s results, where we saw similar trends:
    http://northerngrapesproject.org/wp-content/uploads/2014/02/NyMarqTrain.pdf
    Will post more photos at a later date.

  • John Marshall

    I see that the results on HWT vs VSP suggests strongly that the earlier veraison, better ripening and larger and stronger buds are a result of poorer sun exposure. All these would result from poor sun exposure.
    I question that with shoot positioning, shoot removal, leaf removal we cannot get much better sun exposure with VSP than with HWT. It would take more cultural time and expense, to be sure, but it would give growers a clearer idea of the two trellises and what their potentials are .
    The HWT was developed for Labrusca grapes and takes advantage of the drooping or trailing nature of this family of grapes. however, vitis Vinifera are extremely upward growing and cannot really be trained from the high wire. Many hybrids retain some or much of this upward growing and are not so well adaptable to this Labrusca-type trellis.
    If through hedging, shoot positioning, shoot removal and leaf removal the results still showed earlier veraison, better ripening, larger and more numerous clusters on the HWT than the VSP, this would be an impressive result but the pictures i have seen have not illustrated this clearly at all.
    It has illustrated what Dr.Richard Smart proved sometime ago that sun exposure is critical to complete ripening and high quality fruit. If you can prove it is inherently impossible to get good sun exposure growing hybrids on VSP, then that would be an important piece of knowledge. Or if you prove that with the extra time and work of canopy management you can get better results on VSP, that also would be important. However, from what I have seen so far, this study’s conclusions (HWT is broadly superior to VSP) are painted with far too broad a stroke.
    John

  • tem2@cornell.edu

    Thanks John for your followup comment.
    I appreciate your opinion that the VSP in 2013 was shaded, but that wasn’t the case. We did agressive leaf removal (3x), hedging, and shoot positioning. And the fruit chemistry numbers (except for brix, which is heavily influenced by cropping level) – pH and TA – came out the same. Reduced bud fruitfulness related to shading is one hypothesis, but I’m not sure it explains why all the yield components (including berry weight) were lower in 2013. Another possible factor is that downward pointed shoots are devigorated (compared to upward) and that this altered the allocation of carbon between the shoot tips and clusters. I honestly don’t know.

    BTW – not making any claims beyond ‘here’s the data we have gotten from our trials in 2013.’ We also have trials in IA and MI, and it will be great to be able to see results across those three sites. We are set to continue for another 2 seasons.

    Thanks again for your comments.

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