Tasks for the Slow Season
The winter season for most growers is the time of the year where they can relax, let their hair down, and even head to tropical cities to unwind. This year, it will be a well deserved vacation, with a record harvest, thanks to ideal growing conditions. However, there are a couple of things that you should do before you head out with your sunscreen and Bermuda shorts.
Now is the time to plan your strategy for pruning. With some juice grape growers in an overcropping situation this year, vines may have been stressed by this excess crop load. Depending upon the vine performance, you may think about balance pruning a couple of vines to figure out what the vigor is, and then leave more or less buds to compensate.
Balanced pruning is a concept that many have heard of, however a brief review is always helpful. Balanced pruning is a concept used to properly balance the vegetative and reproductive growth of a vine, based on the previous season's growth. Thus, if a vine had poor growth during the season, perhaps one would want to prune a bit harder to encourage vegetative growth the following year. However, if the vine was very vigorous, more buds could be left to induce a better balance between potential crop load and leaf area.
On a normal Concord vine, approximately 50-60 buds are left on a vine, and anything more than 90 buds per vine could lead to reduced fruit quality and uneven ripening. Actually, many of the balanced pruning formulas were developed for Eastern US growers where they can often run into problems with vigor and overproduction. Concord growers in Washington could actually leave more buds than typically recommended by the published balanced pruning formulas.
In V. vinifera grapevines, it can be quite a bit lower, depending on your variety. Some suggest a 20+20 formula, while in warmer climates; a 10+10 formula is sometimes used. The important thing to remember is that you prune according to the vigor of your vine, and in the process, remove about 90% of your current season's growth.
Winter is the perfect time to get out there and clean up your chemical storage. This is especially true if you have multiple crops with multiple demands – it never seems to stop. With the revisions of the Grape Pest Management guide due out in January, 2006, start looking at any of the chemicals that may not be needed or are being phased out and dispose of them properly. The Washington State Department of Ecology has a website at: http://agr.wa.gov/pestfert/pesticides/WastePesticide.htm .
Monitoring soil moisture is also a necessity as many growers found out this past growing season. Some researchers maintain that climate change is upon us and that droughts will continue to plague irrigated agriculture in the US . So far this year, the water situation looks promising and ski resorts are open. However, the weather is not predictable, and we could end up having a dry winter in central Washington again this year. Be sure that your soil water profile is full at the beginning of the season around bud break to avoid uneven growth. However, everything comes with a caveat, and that is if you are in a chlorosis-prone vineyard, monitor soil moisture carefully as to not induce chlorosis.
Remember that winter is a great time to catch up on all that you're too busy for during the growing season. Here is a short list of the main tasks that should be completed in preparation for the next growing season:
Winter Checklist:
• Assess vine vigor to determine pruning strategy
• Make sure pruning blades are sharp for handheld or mechanical pruning
• Clean chemical storage shed; Dispose of waste products properly
• Monitor soil water status and precipitation to determine water strategy for next year
• Go through vineyard and replace dead/diseased vines
• Complete any necessary repairs on the trellis system and irrigation wire supports
• Mow vineyard and level out gopher holes if necessary
• Trapping and release programs
• Keep up on maintaining pesticide credits with annual meetings and lectures
• Learn about the latest technologies with tradeshows and annual meetings
Good luck and here's to a great season next year! Happy Holidays!
Mercy Olmstead, WSU Extension Viticulturist
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