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Grape Chores – Fall 2019

UGA Extension Viticulture Blog

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Reflection on past: The 2019 vintage was warm and dry throughout the southeastern (and most of the eastern) U.S. The 2019 vintage was highly divergent from that of the previous two vintages, which were characterized by greater cloudiness and rainfall. Thus, depending on harvest decisions, wines from 2019 may be less acidic and perhaps riper in character relative to 2018 and 2017. Like in 2010 and 2016, the post-veraison period was characterized by sustained periods of heat and sunlight, weather patterns not observed in all vintages in the eastern U.S. Such weather patterns were likely to result in greater concentrations of sugar and varietal character compounds, particularly for red cultivars. As we all know, vintage variability is the name of the game here in the eastern U.S. I am glad we were on the “good” side of variable this year… we may not be so lucky next year.

This grape chore list will last through January/February, when the next installment will be released through the Southern Region Small Fruit Consortium website (www.smallfruits.org).

  1. Update records and double check that you have recorded the crop yield and chemistry from all blocks and varieties.
  2. Ordering vines for vineyard- or block-sized plantings. It actually may be a bit too late to guarantee that a certain cultivar will be available for spring 2018 planting – especially if you are after a particular clone/rootstock combination.  Nursery orders are best-placed about 18 months before planting date to increase the chances of getting the desired cultivars/quantities – especially with niche cultivars like Blanc du Bois, Lenoir, Lomanto, Petit Manseng, Petit Verdot, Crimson Cabernet, and Albariñ  However, it is better to try and inquire today over tomorrow.
  3. Ordering materials for new vineyard. Newly planted vineyards require several materials for efficient and successful establishment. Posts, staples, wires, grow tubes/vine shelters, training stakes, tying materials, irrigation tubing, herbicide, etc. are all necessary to have on hand when planting a new vineyard. Some materials are more important to have on-hand pre- relative to post-planting, but why wait to order when you know you will need certain materials anyway?
  4. Identify systemically infected vines and flag / rogue out before leaf fall. Foliar symptoms of vines infected by bacteria, viruses, and phytoplasmas can only be visualized before leaf fall. Thus, if it hasn’t been done already, walk your vineyard and identify and flag symptomatic vines.  Vines from Georgia vineyards can be tested for PD in the White and Lumpkin County, GA Extension offices.  There are currently limited remedial treatment options for vines infected by bacteria, viruses, and phytoplasmas except to monitor and control potential vectors, and to rogue out infected vines to limit local inoculum source.  Like in 2017 and 2018, we have seen many cases of Pierce’s disease (PD) here in Georgia this year, and this is likely due in no small part to the mild “winters” we have recently experienced.  Our current recommendation for Pierce’s disease is to immediately rogue out the symptomatic vines. See this extension publication for more on Pierce’s disease of grapevine.

    Pierce’s disease in Chambourcin

     

    Undiagnosed, systemic disease in Merlot

     

  5. Post-harvest disease management. Post-harvest disease management aims to maintain carbon assimilation before leaf fall, when the canopy is transporting mineral nutrients and carbon to the permanent vine structures. The primary culprits of diseased canopies are downy and powdery mildew.  How do you know if you need to spray post-harvest fungicides? My two cents are that if you have clean foliage going to into harvest, then it may not be necessary to spray fungicides after harvest.  However, if your disease pressure is high, then spraying appropriate fungicides may help maintain foliar health to maintain photosynthesis. One or two post-harvest / pre-leaf fall fungicide sprays are likely sufficient to maintain canopy health and prevent excessive inoculum buildup. Canopies should be in better shape this vintage than the last two vintages given our low disease pressure in 2019.
  6. “Winterize” equipment. Take down bird netting and store so that it can be easily deployed next season when the bird pressure begins. “Winterize” (clean, grease, etc.) tractors and other mechanical and manual vineyard and winery equipment (picking bins, hedgers, mulchers, mowers, sprayers, picking shears, appropriate winery equipment).
  7. Evaluate trellis integrity and repair. The trellis has taken a beating and has supported a lot of weight throughout the season; this is particularly true in locales affected by Hurricane Florence or Michael. Check for broken posts and trellis wires and repair or replace them before next spring.
  8. Evaluate missing vine number and order replants. You may have already pulled vines out due to infection or physical damage, general undiagnosed poor/weak growth, or vine death. Walk the vineyard and count missing vines and order replants where necessary.
  9. Reflect on the season and talk to your regional colleagues – both industry members and extension personnel. What went right? What went wrong? Be prepared for next season by developing a plan to fix the “wrongs” and re-implementing the management strategies that worked well.  It helps to talk to neighbors and ask them their take on their season – they may offer advice and answer questions that will put you in a better position for success next year, and vice-versa.
  10. Dormant pruning. Vines become dormant after the end of leaf fall. However, many may not start pruning until after Thanksgiving or even Christmas.  For those who spur prune, “rough pruning” is a way to get a head start on final pruning.  If rough pruning is practiced and brush is pulled from the trellis wires, the final prune will be a breeze as the short spurs will simply fall out of the trellis onto the vineyard floor.  Rough pruning to 5 to 10 node-spurs allows the grower to delay the final prune to late winter / early spring to assess bud damage and the risk of spring frost. See this extension publication for more on dormant spur and cane pruning grapevines.
    Some “delay prune” by waiting until late winter / early spring before even starting to prune.  This is an attempt to force bud break on the apical bud positions of the dormant cane before those on the basal positions, hence potentially reducing the risk of spring frost damage to the basal buds (i.e. those that will be retained.  We have seen mixed reviews with delayed pruning as it puts growers “behind the eight ball” to finish pruning while several other seasonal tasks are getting underway – it always comes on too fast!  If cane pruning, there is not much logic in delayed pruning, and certainly not much logic in “rough pruning” (i.e. don’t prune the canes you intend to lay out!). Please see this post from the UGA Extension Viticulture Blog, with links to several presentations from last year’s Georgia Wine Producer’s conference, including a presentation on preliminary findings from a delayed pruning field trial in Georgia-grown Chardonnay.
  11. Attend conferences and workshops. The dormant season is a good time to get out and learn from other industry members and university personnel. The vineyard requires less timely inputs from managers during the dormant season and is why most major industry conferences are held between now and March. Here are a few regional conferences in the near future: