It seems just like yesterday that the vines were breaking bud. Harvest is done, wine is fermenting, and the vines are dormant, covered with snow. It was an unusual year at the Rist Canyon Vineyards. After a four year drought, we had a late, cool and wet spring. Buds swelled and burst at the expected times, but shoot growth proceeded very slowly. A one-in-ten year hail storm on the 14th of June stripped leaves, broke off shoots, and either broke off clusters or damaged them. The hail came just as the weather began to heat up. Flowering didn't begin until the 4th of July holiday. A poor fruit set was noted soon afterwards. The Colorado Front Range Foothills then returned to drought conditions. With good irrigation, the vineyard had perfect ripening conditions for the rest of the growing season with the exception of a couple of days of light rain a month before harvest. Birds were an immense problem and bird netting was deployed with great success. Harvest occurred in three stages. The varieties grown at the Rist Canyon Vineyards can be broken down into:

With the leaves gone for the winter, now is the time to evaluate your trellising and training system(s). That's one of the nice things about the end of the season and the leaves dropping. You can now look at the architecture of your vines and determine if your system was appropriate to the growth habit of the variety. I take a look at the way the canes grew. Does it look like they trained to the trellis they way they should for the system you're using? If you're using a vertical shoot positioning (VSP) system, did the canes grow mainly upright and straight? Or did they meander through the the trellis in all directions or outward into the alleyways? Of course, much of this type of growth depends not only on the growth habit but also upon how diligent you were with your shoot positioning.

If you're observing vines growing on a single-curtain of Geneva double-curtain system, are the canes all tangled together or did you "comb" them into the proper position? Shoots on this type of system need to have their shoots positioned just as you would with a VSP system. Positioning drooping shoots also maintains vine balance and proper distribution of sunlight to the canopy.

While your observing the last year's growth, you might also pay attention to whether your canes are wandering deeply into the growth of adjacent vines. This type of growth is indicative of highly vigorous, inbalanced growth. With vigorous growth in a cultivar you may want to consider means of de-vigorating the vine in the next growing season. High vigor vineyards quickly get into a cycle which favors shoot growth over fruit production. Plus vigorous, vegetative growth creates excessive shade that delays fruit ripening, quality of the fruit, and delays hardening of the canes in the late summer and fall.

Vigor can be controlled by some cultural practices. Changing the trellis system to split the canopy, balance the vegetative growth, and allow better sunlight penetration is one of the better means of accomplishing this. Geneva double Curtain (GDC) system for trailing growth habit varieties and the Lyre system for upright growth habits were developed specifically for this purpose.

If you live in a dry summer climate like I do, you can control vigor with irrigation. You can use this technique by creating a water stress after fruit set. By the color change of verasion, active shoot growth can be completely halted. In areas where the summers are moist, planting grass in the alley between the rows is a good practice. This also aids with erosion control. The grass cover crop competes with the vines for water and nutrients. This limits vine root growth and thus controls shoot growth. Different types of grasses utilize different amounts of water so the vineyardist can plant the type of grass that is best suited to his/her conditions of moisture.

Under certain circumstances, higher density planting can devigorate a vineyard. But this only helps if the soils are of low or medium fertility. With high vigor soils this will only aggravate the situation. Lower density spacing with more buds retained at pruning time are right for this situation. It should be stressed that a proper, balanced pruning should be done under all circumstances to control balance to the vines and fruit production.

Observing your dormant vines can give you many insights into the health and condition of your vineyard. You can judge whether you are training your vines correctly. Vigor estimations can be obtained. Decisions on what to change for next year can be made. Plus you have the oportunity to further observe the vineyard in a new phase of growth. I love walking through the vineyard at this time of year. I walk along and think of the pruning to come in the spring, how each vine has grown in the past growing season, and how each year is a new year. I'm looking forward to the new year ahead...

We would love to hear what you think of this issue of Rist Canyon Vineyards Grape Growing Newsletter. And of course, if you have any suggestions for upcoming issues that you'd like to share with us, please send those, too!
Just email me at: ristvin_jrb@ristcanyonvineyards.com

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