Cluster Thinning (Frontenac)

[KevinL]

I know that Frontenacs are vigorous, but I wasn't expecting them to push out shoots with 4 clusters on them.

I've read mixed things about cluster thinning, some saying that it has limited effect on fruit quality and vine health, and others saying that fruit quality and vine health are at risk if no cluster thinning is done. Most of the research I've read has been on Vinifera varieties with longer growing seasons than I have here in Northern Illinois.

4 clusters per shoot seems a bit excessive to me though. For those Frontenac growers out there, how much cluster thinning do you do if any? Before fruit set or after if it is done? How many clusters per shoot do you typically look for?

I know that things generally come down to region/soil/weather and other local conditions. One of my thoughts is just to do an vineyard experiment with some vines getting more cluster thinning than others and seeing where things end up, recording results for future seasons.

 

[NorCal]

Our vines are head trained, we look for 6-7 "arms", 2 shoots per arm, 2 clusters per shoot. Comes out to 24 - 28 clusters per vine. We will shoot and fruit thin to this level.

I am experimenting with single cluster per shoot this year, to see what affect it has on the weight, ripeness, pH etc.

 

[balatonwine]

Cluster thinning on Vinifera is done in conjunction with a lighter pruning. So if you normally prune to 40 buds, then you prune to, for example, 50 buds and cluster thin them. There is not much, to my knowledge, in the benefit : work : quality ratio to cluster thin on an otherwise balance trimmed vine.

Side note: I do not know about hybrids. Or if 4 clusters is too much or not.

 

[Masbustelo]

I have a little experience with Frontenac. I helped pick Frontenac at a commercial vineyard a few years ago. It looked to me like they had pruned, sprayed and then done nothing else. Frontenac is extremely vigorous, and to even be able to get close to the vines to harvest, they went down the rows with a chainsaw and cut out lots of the growth. It was hard to pick and wasn't particularly overly productive. I have no idea how it should properly be managed or if it can be. As a stand alone red wine Frontenac hasn't been extremely popular. Where I helped pick they used it to make Rose, and I have read that it makes a very good port.

 

[BigH]

For those Frontenac growers out there, how much cluster thinning do you do if any? Before fruit set or after if it is done? How many clusters per shoot do you typically look for?

Well, I only have one successful frontenac harvest season under my belt, and 2 failed harvest seasons (lack of spraying program and lack of bird netting), so take that into account. Here are my opinions on frontenac:

1. My Frontenac seems to have no trouble making 25 brix
2. Acidity is the dominant harvest parameter for Frontenac. I really want to see the TA dip below 15.0
3. To get the acid down, Frontenac needs to hang on the vine into mid September (central Iowa). It is the last variety I harvest
4. To get the acid down, Frontenac clusters need to get some sun.
5. Frontenac is incredibly vigorous and needs a heavy crop on it to keep the vigor down

I do cluster thin my Frontenac after berry set. Items 2 through 4 from the list above are what really drive my thinking. However, I don't want to remove too many clusters, or excess vigor becomes a problem.

My Frontenac is on a GDC trellis. I remove all clusters from really weak shoots. I keep 1 cluster on shoots that are 12-18 inches long, 2 on decent shoots longer than 18 inches, and 3 on hyper vigorous shoots in the head area if I think all 3 clusters will get decent sun (this tends to be a rare choice).

I personally don't keep that fourth cluster, if it shows up, simply because I know it developed last, and it seems like I will have a hard time getting his acid down before the the top cluster above him starts dimpling and getting scorched from the late summer heat. I would rather have a reduced crop of uniform quality than a large crop.

Here are the other canopy management practices I use with frontenac

• shoot thinning to 6 shoots per foot
• little to no weed control
• I usually keep a "kicker" cane from the mid trunk area
• shoots get hedged near the ground
• I do some leaf pulling in August.

These practices produced a crop that had these harvest parameters in 2017: brix 25, pH 3, TA 12.2, 21.8 lbs of grapes per vine.

Good luck. Let us know how it goes
H

 

[KevinL]

I have my Frontenac on a TWC. Weed control is weed whacking only with a little weeding at the trunks so I can pinch off suckers if they pop up. When the shoots reach the ground, they have a tendency to get hit with the lawn mower, and weed whacker, but other than that I don't pay too much attention to what they're up to.

Last year I panicked and harvested what little I had left early as the chipmunks were getting to the last few bunches. I wanted at least something to experiment with. I lost a lot to black rot pre-veraison, and then even more to birds and chipmunks after.

I did no cluster thinning (Last year at most there were 2 clusters per shoot), I didn't pull any shoots, and I did some leaf pulling in August.

25 degrees Brix, 3.14 pH, and a TA of 15. Harvest date of 9/11.

I would have preferred to let them sit on the vine longer. This year I've got my "pool of death" traps all ready to help control the chipmunks, and nets for the birds so I should be able to defend them.

I think I'll hang on to the fourth cluster this year as an experiment and pull a sample from strictly 4th cluster grapes, and also from strictly 3rd cluster grapes and see if there is a difference between them and the remainder. I do have some vines near the edge of my property that get less sun than others and I'll leave them out of the experiment for the sake of having more useful information in general. My vineyard is not large enough for me to try to test other variables at this point.

With regards to the style of wine, I have had fabulous Frontenac ports, and so I may move them into that style. The batch I have now from my limited 2017 harvest is still really acidic (Even After MLF, Cold stabilization, and K Bicarbonate), and I think I'll back sweeten it to make it serviceable. If it just ends up making a sweet red, then so be it. I'll be happy with something that tastes good and has unique flavors.

 

[BigH]

I have now from my limited 2017 harvest is still really acidic (Even After MLF, Cold stabilization, and K Bicarbonate), and I think I'll back sweeten it to make it serviceable. If it just ends up making a sweet red, then so be it. I'll be happy with something that tastes good and has unique flavors.

What is the pH and TA now? What yeast did you use? Did you verify MLF success with a chromatograph test?

Understand the consequences of sweetening a wine that has underwent MLF. Potassium sorbate plus residual ML bacteria is reported to be a recipe for off flavors.

H

 

[Stressbaby]

Following this thread as I'm allowing 1 cluster/shoot on my hyper vigorous Frontenacs in this, year 2. Good info.

MLF + Sorbate = geranium. Been there.

 

[BigH]

MLF + Sorbate = geranium. Been there.

I would like to use MLF to munch down some acid in my Frontenac Blanc, and then later backsweeten it a touch. Is there a safe way to do this? Suppose I verify MLF completion, rack off the MLF lees, add sulfites, and age for a few months with a few more transfers while maintaining proper SO2 levels. Do I reach a point where it is safe to add potassium sorbate? I thought I read that you get the germanium taste when ML bacteria actively ferment something in the presence of sorbate. Am I safe if I kill and remove as much ML bacteria as I can, and verify that there is no more malic acid for them to consume?

I face a bit of a dilemma with my 2017 Frontenac Blanc. I had hoped to make a midwestern chardonnay clone with it. Like a fool, I decided not to ferment with 71B and instead chose a chardonnay yeast (ICV-D47). I figured my acids were low enough that MLF would take off, and I didn't need 71B's acid munching power. Well, the MLF failed. Not sure what I did wrong. The pH was around 3.15 which I thought MBR 31 could tolerate. I can kill some of the remaining acid with acid-x, but the wine really should be sweetened.

I am essentially in the situation I describe in the first paragraph, except the part about MLF completing

H

 

[Johnd]

I would like to use MLF to munch down some acid in my Frontenac Blanc, and then later backsweeten it a touch. Is there a safe way to do this? Suppose I verify MLF completion, rack off the MLF lees, add sulfites, and age for a few months with a few more transfers while maintaining proper SO2 levels. Do I reach a point where it is safe to add potassium sorbate? I thought I read that you get the germanium taste when ML bacteria actively ferment something in the presence of sorbate. Am I safe if I kill and remove as much ML bacteria as I can, and verify that there is no more malic acid for them to consume?

I face a bit of a dilemma with my 2017 Frontenac Blanc. I had hoped to make a midwestern chardonnay clone with it. Like a fool, I decided not to ferment with 71B and instead chose a chardonnay yeast (ICV-D47). I figured my acids were low enough that MLF would take off, and I didn't need 71B's acid munching power. Well, the MLF failed. Not sure what I did wrong. The pH was around 3.15 which I thought MBR 31 could tolerate. I can kill some of the remaining acid with acid-x, but the wine really should be sweetened.

I am essentially in the situation I describe in the first paragraph, except the part about MLF completing

H

The safest solution to the problem is to not use sorbate, and to sterile filter the wine, thus removing any yeast cells that would be capable of metabolizing the sugar you sweeten with. You do not want to add sorbate to a wine that has undergone MLF, whether it finished completely or not is immaterial.

 

[user 36973]

This is the first year my frontenacs are producing. Due to their vigor, I will not be thinning fruit. Ask me again in October if I thought this was a bad idea.

MLF + Sorbate = geranium. Been there.

Do I reach a point where it is safe to add potassium sorbate? I thought I read that you get the germanium taste when ML bacteria actively ferment something in the presence of sorbate. Am I safe if I kill and remove as much ML bacteria as I can, and verify that there is no more malic acid for them to consume?

The geranium taint occurs when MLF metabolize the sorbate. So the key is to not add sorbate until the MLF bacteria are dead. Fortunately sulfites work wonders in killing them off. I have not personally back-sweetened and sorbated a wine that I put through MLF, but Presqu'Isle has an article that discusses this here. So it CAN be done with careful timing and by maintaining sufficient sulfite levels.

 

[KevinL]

What is the pH and TA now? What yeast did you use? Did you verify MLF success with a chromatograph test?

Understand the consequences of sweetening a wine that has underwent MLF. Potassium sorbate plus residual ML bacteria is reported to be a recipe for off flavors.

H

I didn't get my yeast beforehand. I panic harvested so I think I ended up using Pasteur Red or something. Whatever I had around at the time. I should have written it down, but at the time I figured I intended on researching a high TA friendly yeast to use on my harvest. I'll happily take recommendations.

I haven't tested TA recently, but last time I did it clocked in at 10.5. I did not verify MLF success with a Chromatograph test. I'll be ordering some strips soon once I get a list together of all the things I'm going to need to be ready for this years harvest. I'll pull a sample and run some tests and report when I know.

With regards to sweetening, I am aware that you're not supposed to use sorbate after MLF. I was just going to pull a sample and add some simple syrup to it and see if it took off. If it managed to stay stable for a while I would figure that It wouldn't blow the corks off if I bottled it. If it is true that once the MLF bacteria are dead it is safe to add sorbate, then that is what I would prefer. It seems as if it has been a discussion on these boards in the past: https://www.winemakingtalk.com/threads/k-sorbate-in-mlf-wines.19203/

Since we all like pictures I'll get out in the vineyard and take some of the clusters as they are developing.

 

[BigH]

I am getting close to bottling my 2017 Frontenac that I made into a dry red. pH was at 3.4 and the TA measured 9.0. Books and conventional wisdom say that TA is on the high side, but I really like the way this wine tastes, so I am inclined to leave it. Thinking about bottling 3 of my 5 gallons as is, and saving off a couple gallons to experiment with blending, probably with St Croix or Petite Pearl.

I used the other half of my Frontenac to make a Rose. We won't discuss that. It is has been a bit of disaster to this point.

H

 

[Stressbaby]

I am getting close to bottling my 2017 Frontenac that I made into a dry red. pH was at 3.4 and the TA measured 9.0. Books and conventional wisdom say that TA is on the high side, but I really like the way this wine tastes, so I am inclined to leave it. Thinking about bottling 3 of my 5 gallons as is, and saving off a couple gallons to experiment with blending, probably with St Croix or Petite Pearl.

I used the other half of my Frontenac to make a Rose. We won't discuss that. It is has been a bit of disaster to this point.

H

Let's discuss that. I intend to make rosé from mine.

 

[user 36973]

A couple years ago I made a Frontenac Rose when a grower called to say he had 1700# he could bring by the next day. No real issues overall for me. The color was quite dark for a rose even though I crushed and immediately pressed.

I managed the acid with sufficient pot bicarbonate to bring TA to about 10g/L before fermentation. Cold stabilization took it to 8.1g/L. Ended up back sweetening for balance also. Nice cherry flavor.

 

[BigH]

Let's discuss that. I intend to make rosé from mine.

This was my first attempt at a rose. I started by keeping the juice on the skins too long, so my juice was almost as dark as a red. I have been blending it over time with Frontenac Blanc to bring the color back to where it should be. I pitched QA23 yeast because I read that it is a good rose yeast and my plan was to use MLF to bring down the acid. The MLF failed to complete just like it did for my blanc, despite temperature control and ML nutirents. I wish I had used 71B to bring the acid down and skipped the MLF.

The taste is really sour. I am doing a cold stabilization now. Planning to blend a bit more with a white to further thin out the color and round out the potency of the remaining malic acid. Will eventually need to back sweeten somehow, where I face the same dilemma as I mentioned earlier..

H

 

[KevinL]

As promised, here is a photo of one of my four cluster shoots. Even with that many on there, the vine is having no trouble pushing out plenty of vegetation.

We'll see how the numbers develop as they ripen.

 

[marquettematt]

AS far as vinifying goes, I can't give much advice but growing Frontenac is a different story. I usually get 3 cluster shoots. In their 5th year I pruned them down to 2 cluster shoots with 7 or 8, 2 bud spurs on 2 arms. It was relatively disease-free, but I could see the over-cropping effect the next year. 75% bud kill from winter damage after a winter low of -3 or 4. I made the mistake of counting on that bolstered winter hardiness to save the vine in case I over-cropped. Its year 7 and it recovered nicely. I pruned the same but only 1 cluster per shoot. As rule of thumb, you should cluster thin outer to inner and you should thin it pre-bloom. If you're getting 4 clusters per shoot in an area that gets relatively less light intensity ( I say that because light intensity is a big factor on next years productivity), you have a healthier site. 2 clusters might be fine but don't be surprised if you get winter damage. Over-cropping can be detrimental to vine health and fruit quality. The ripening fruit becomes a sink for nutrients and can spread the vine too thin. Some vines are hard to over-crop. Frontenac is not such a vine. What I do know about making wine with it is this- let the fruit hang as long as possible and get that acid down. It also helps dissipate the herbaceous flavors associated with fronenac.. IIRC, Peter Hemstad, the breeder from U of MN who created that vine among others, said that it is best blended with Marquette

 

[KevinL]

That is interesting From what I've read and talked to other growers about, I was under the impression that you couldn't kill Frontenac even if you tried (One guy told me he was trying to kill his and hosed it down with round up only for it to take off like nothing had happened.) I've gone and cluster thinned a few of the vines, (Granted I only thinned one pre bloom) and I will compare them with the ones that received no such treatment. Due to my spray program managing the black rot, this is the first year I've had where I've got more than a little to experiment with. I'm willing to risk the health of the vines as long as they're not going to die completely. For Science!

On Vinifying:

I just bottled my 2017 Frontenac (what little of it survived the black rot, birds and chipmunks). I decided against back sweetening as I found I really liked the taste of it as is. It smells like blueberries, and tastes like pepper. Very interesting combination. I rather enjoyed it, and it might have a bit to do with the fact that this is the first wine I've made from grapes from my own vineyard so I might be a bit biased. Ended up with a whole 3.5 bottles of it. I neglected to get the chromatography paper so I can't confirm if MLF was successful.

Final numbers: pH: 3.38 TA 8.25 g/L. I did dilute with a sugar/water solution on the front end before fermentation to help a little bit with that. I only did a little bit as i was worried about my pH getting too high. I also threw in what little Vidal Blanc I harvested last year as well (Wine is 89% Frontenac and 11% Vidal). As primary finished, I added the Malolactic culture. Unfortunately I didn't write down the specifics on it. After the racking I ended up adding a bit of water to top it off (not much). At this point I only had one gallon. I stuck it in my root cellar in the winter where the temperatures go very close to freezing. At this point the TA was at 10.5. I degassed it with a vacuvin hand pump and then I added K bicarbonate and Oak and returned it to the root cellar for more cold stabilization. After two more rackings it now sits in it's bottles read to drink in my opinion.

Harvest date 9/11/2017 - Bottled 6/30/2018.

I'm sure I screwed up countless times in this process, but I must say I thoroughly enjoyed the entire process and having bottles of wine on my rack from the vineyard.

Lessons Learned: 1. Write down the yeast used and be prepared ahead of time for harvest. 2. Write down the MLF information and be prepared to confirm if it is completed. 3. Anything dry over 11 g/L TA tastes like a punch in the mouth.

I'll have a much longer list of lessons by the end of this harvest season as well.

 

[BigH]

Congrats. Might want to adopt a good logging strategy. I use google sheets so I can access my win log from a variety of devices.