2015 Vintage Update - Shoot Thinning and Suckering

Well it's not yet through April yet and I have lots to report. If you've followed my last blog about the current

vintage you know that we're still watching for frost. That will last until mid-May. The intention of this article is to discuss observations about the vintage and what we're doing to keep things moving along. Anything can happen, and we have had one morning that was borderline freezing a couple of Sundays ago. On the south side of our vineyard there's a swale that runs through our newest Pinot Noir block. Mother Nature nipped the edges of a few leaves. If you take a look at this photo you can see a small brown burn mark on the edge of the leaf. Also, part of the leaf edge near the brown is missing. This is frost damage. Frost can happen at any time but it's most prevalent in the Willamette Valley between Bud Break and May 15th in any given year. If you have extensive damage you can lose the entire primary node or bud. If this happens, as I've discussed before, a secondary bud will come out on roughly half of the affected plants. This is the plants way of surviving until the next vintage, but a secondary will likely be behind the rest of the year and not produce much fruit. So, if a wine grower has extensive frost damage they usually will have a tough couple of years to follow. Frost will affect multiple years if the damage is severe enough.

What else are we looking for at this time of year?

Besides frost damage, we're also looking for any mite or other animal damage. This time of year we're extremely vulnerable to all sorts of animals including deer, rabbits, and a plethora of insects. I've found some Erineum mite damage in the same block with the frost damage. Erineum mites, more commonly referred to as Blister mites, can infest a vineyard if they aren't properly managed. They usually start in relatively small areas, but left unchecked can grow into quite a population. You can identify mite activity by the blister looking bubbles on leaves. The adult version of these mites will winter over under the scales of buds. Elemental Sulphur is a good control mechanism for populations of this mite. If the infestation becomes worse you can also remove affected leaves, but it's usually not needed. With the speed everything's moving at right now we're looking at several different issues at the same time. Let's move on to shoot thinning and suckering.

In this video, Maria looks at a Riesling plant that was started back in 2006. It's mature now, and what we would typically be looking at in mid May we're looking at right now. She checks the individual nodes to see if they are putting out any secondary shoots. If they are they get removed. Then she looks at the head and the trunk of the plant suckering any shoots that the plant might put out. With an early start this year we will probably have to go through and sucker more than once. If we go along and shoot thin and sucker before the shoots get 4-6 inches out we can just remove them with our hands. If we wait the suckers will harden off and then have to be removed with pruning shears. Why are we doing all this? The simple answer is canopy management. The slightly longer answer is that we're trying to control the density and position of the canopy as it starts to form. This is the easiest time to do it. A lot of work on the vines at this stage will create a much easier situation in the summer. The single biggest fungus associated with grape growing in Oregon is powdery mildew. Powdery mildew cannot be easily controlled once it rears it's ugly head in the vineyard. The best way to stop it from forming is to choose a site that has multiple wind directional changes throughout the day. This allows the canopy to dry out naturally and not give mildew an inviting environment to develop in. That's why many vineyards in Oregon are situated near coastal wind channels up and down the Coast Range. The next best way to control mildew is through canopy management. By thinning out our canopy now we are helping to create an open canopy that easily dries out in the morning.

"Density is our enemy in the vineyard, much like oxygen is our enemy in the winery." 

Suckering goes to the same end as shoot thinning. We want to control position and density of our canopy.

The plant will put out new shoots of growth every year. The one's put out on the base of the trunk are useless to our end goal and are difficult to spray. There's some science out there that contends you need 17 leaves to ripen one cluster of wine grapes. I can't remember if that's the exact number, but the point is that there are plenty of leaves in our canopy to ripen the fruit that the plant will set. There are too many! So, we sucker, shoot thin, and then later in the summer we will even cut off the tops of the shoots to control our canopy density. Suckering the plant gets rid of these useless shoots that the plant puts out. We want to do it early again because it's easier right now. As the shoot grow they will harden making them more difficult to remove. The photo above is of a 45 year old Riesling trunk. You can see the suckers coming off the side of it. These will need to be removed.

What's Next?
We have a ways to go for bloom, the next milestone of this vintage. In my timeline though, our next step will be to cultivate the ground between the rows with a reverse tyne roto tiller. That will happen the first week of May, weather depending. This will release Nitrogen, Hummus, and other micronutrients into ground along with additional water to help the plants thrive through the summer. IF you're enjoying this series of articles please do let me know by adding a comment. Until next time...