Wednesday, September 29, 2010

Zweigelt or Zweigeltrebe

This is a grape of Austrian origin having been crossed by a fellow by the name of Fritz Zweigelt in the early 1920's. The vine is a cross of Blaufrankisch and St. Laurent. The vine is a very heavy producer and can crop at 5-6 tons per acre.

references suggest that this vine has late bud break and is relatively early ripening, a few days before Pinot Noir and a week after Regent. The vine is also reported by some who grow it (Peter Salonius and Paul Troop) to have some practical mild disease resistance to the common mildews and is relatively cold hardy to approximately -20c. The grapes from the vine is also reported to make very good wine and the Zweigelt I've tried from Arrow Leaf cellars in BC is quite good - of course this is subject to the skill of the winemaker and quality of grapes.

We've got a few Zweigelt vines planted at the test vineyard now after acquiring some cuttings from Paul Troop of Omega Vines (see links on the blog) in the spring of 2010. In general the vines are strong and vigorous, and we'll see how they make out the winter and bud out next year.

This vine is suited for only the best location at our site with the longest frost free days and greatest accumulation of degree days. This would be on the upper bench which is about 100 feet above the test vineyard. The upper bench appears to average about 10 percent more degree days. Our test vineyard seems to be averaging about 140-145 frost free days and 900-950 degree days so it could be extrapolated that the upper bench has about 1000-1050 degree days and perhaps a slightly longer frost free season.

This frost free days and degree days status of the test vineyard is likely not enough for this variety based on trials at Mt. Vernon, Washington where 1000 degree days is recommended. Also, a grower in New Brunswick gets about 900 degree days and 140 frost free days and it barely ripens most years. As such, I've planted one of the Zweigelt vines on the upper bench and will use that to compare the growth stages with that of those in the test vineyard. Going to add a few of the other varieties up there as well (Castel and perhaps transplant one of the Pinot Noir as well) again to see the difference in growth stages between those on the upper bench and those in the test vineyard.

Saturday, September 11, 2010

Clearing of the Land - Changing Mesoclimate

In this past spring we cleared out approximately 0.5 acre to open up the area around the vineyard. There were several reasons for this. First the larger opening in the forest should foster a higher degree day accumulation in the vineyard. Secondly it would allow the cool air that gets trapped behind the trees to drain away from the vineyard. Lastly it would provide more morning sun, as the tree to be cleared were those to the east of the vineyard.

We cleared the trees at the end of April and we were finally able to see the lay of the land around the test vineyard. To our surprise we found out that the area of the test vineyard in in a small low spot and is prone to cold air accumulations in spring and fall - naturally this is my luck. This also means that the larger opening we created now provides a greater area to drain cold air into this low spot that the vineyard is in and heightens the frost potential.

So now we were faced with trying to eliminate the amount of cold air that flows off the mountain side and settles in the large opening surrounding the vineyard. There are a few measures that can be taken to mitigate this. First, we have cleared the rest of the trees out to the edge of the valley drop off, about another 0.5 acre. The bench that the vineyard sits on is approximately 100-120 feet above the lower valley below. Clearing these trees out has changed the movement of air dramatically. If you stand at the low end of the clearing at the edge of the valley drop off after the sun goes down you can feel the rush of wind moving down the valley and through the vineyard and the clearing and over the edge to the valley below. Clearing the cool air away is a good start.

The picture below is of the valley below the Lower Bench in winter. You can see the warm air fog that has formed in the middle because the cold air is filling in the low area. The Lower Bench that the test vineyard is on is to the left of and 100-120 feet above the road. There is another bench, the Upper Bench, which is separated by a gravel road and it is another 100-120 feet above the Lower Bench (see image below).

Next we want to limit how much cold air enters the vineyard and the clearing. So we are planting a large wind break hedge at the upper end of the vineyard clearing to deflect the cool air that otherwise flows down the mountain and enters the vineyard. This will take a few years to grow and to have some effect but in the interim we are discussing erecting a mesh or wood wind break to do the same thing. The one we build will not be as high as the tree hedge but should help deflect the cool air to some degree.

We placed temperature data loggers down slope from the vineyard towards the valley drop off and have found that the area just down slope from the vineyard (but out of the low spot that the vineyard is in) registers between 0.0 - 0.5 degree warmer each night. Also, a second data logger placed near near the bottom of the slope registers between 0.5 - 1.0 degrees warmer than the vineyard for overnight lows. Another placed in a clearing on the lower valley bench registers night temperatures 0.5 degrees colder than the vineyard. It appears that allowing the cold air to drain away provides warmer night temperatures in the vineyard but in addition there may be some warm air funneling into the clearing from the bottom end of the slope as it rises up from the valley below.

We have recorded similar but more dramatic readings when we placed a data logger on another part of our property. This area is a smaller bench that is approximately 100 feet above the vineyard. The data logger at this level has consistently recorded night time lows that are 2.5 degrees warmer than at the vineyard location in June, July, and August - no winter records have been taken.

While it is nice to see these warmer night time temperatures at different locations on the property, where we'd really like to see them is in the test vineyard. With out getting into wind machines or artificial heating of the air the best we can do to reduce cold air in the low spot of the test vineyard is to provide a place for the cold air to go. Also we can to try to limit how much cold air enters that area. Clearing the land for air drainage and creating a wind break hedge to deflect cold air should help with these.

At the same time we know that if the vines grow well in the test vineyard, then climatically speaking they should grow great in the other warmer locations.

Saturday, September 4, 2010

Kootenay Covers Netting for the Grapes

Its all but certain that sometime some birds are going to find out that there are grapes ripening in the vineyard. We've got several varieties of grapes growing that are both subject to attack by birds and insects (waspes in particular). As such, we were looking for a vine cover that both protects from birds and wasps but also allows the sunlight through so the grapes can ripen. See photos below,

We researched many potential grape covers and there are some that both protect against birds and insects and let sufficient light through (over 90%) but we discovered a locally designed cover through Kootenay Covers
Kootenay covers makes covers for grape vines and fruit trees and their product protects from birds and insects and lets signifiucant light through. I don't have figures on how much light goes through this product but it is substantial and I'd estimate between 85%-95% of the light goes through.
One of the hopes with this product is that it may provide a small degree of frost protection at the end of the season. Even 1 degree of frost protection can make a huge difference in staving off that first frost and allowing the grapes to ripen perhaps another week.

We deployed the netting in late August and did some preliminar tests on the overnight temperature profile between the covered row and the uncovered row beside it. We checked the temperatures hourly after sunset until about 11 pm / midnight and found that overnight lows were the same for the covered row and uncovered row except that the neeted row stayed warmer (1-2 degrees) longer into the night then drops off fast and equals out to the uncovered row after 11pm.

We'll do some more testing as the frost season approaches and report back. So far we really like the covers. They appear to be very durable, easy to deploy and the cost was significantly less than other similar products. Check out this link to Kootnay Covers.