Summer Fungiside Spray for Marquette and Marechal Foch

[kartracer088]

This is my third year for my vines and hoping to to get a crop to harvest this year. They look healthy so far and I had been treating with Mancozeb up to this point but stopped because of the pre-harvest interval. So what can I use up to near harvest?

Thanks in advance,

 

[Cynewulf]

I guess it depends on where you are, the kind of disease pressure you face, and what you’re spraying for. Keep in mind that mancozeb has a PHI of 66 days so if you’ve been spraying it into veraison I think you may have exceeded that. I spray with mancozeb and sulfur for my first six applications then switch to immunox (14 day PHI) and Captan (0 day PHI). Grapes also develop ontogenic resistance to black rot, downy mildew, and powdery mildew somewhere between 4 and 6 weeks after bloom so you won’t have to worry as much about those on your clusters, though you’ll still want to protect the foliage if it’s threatened.

 

[kartracer088]

I stopped spraying the mancozeb when I saw the initial bunches start to color change. Most of the crop is still very green. But you bring up an issue that I have not been able to find much information.

1. How do you determine when harvest will be so you can observe the PHi?

2. When do you start counting the number of days of the growth cycle?

I have Marquette and Marechal Foch. The Foch seems to be well behind the Marquette. I have not been able to find any information on how many days the growth cycle runs.

Additionally, we had a late freeze this year in early May. Literally all the chutes fell off. I didn't think there would be any grapes this year, but many of the vines produced new chutes with grapes.

 

[kartracer088]

I found this note in an OSU newsletter.

https://ohiograpeweb.cfaes.ohio-sta...ce/pdf_newsletters/OGEN_06_June_2013_(24).pdf
NOTE: Do not apply Captan, sulfur or copper fungicides within 30 days of harvest or fermentation
may be affected and DO NOT combine Captan or Sulfur with any form of oil.

 

[Rice_Guy]

I gauge PHI by recording where it was last year and this year started adding anniversaries of garden pick start to the computer calendar

 

[Cynewulf]

I think 1 will come with time as you keep good records and learn about how the varieties you have grow in your particular vineyard with its climate and conditions. I’m still figuring out what Marquette does in my little vineyard in Virginia. This year the more vigorous vines I allowed to ripen a little fruit saw veraison around July 4 then by July 27 were at 23 Brix and pH 2.8 and the bugs and birds were starting to set in. My Carbernet Franc has not started veraison yet but talking to other growers near me makes me think it will begin in another week or so but every year will be different. The issue with mancozeb isn’t just the PHI but also that you’re limited to 6 applications a year. For me that meant that my last application of mancozeb was the last week of May.

I’m not sure I understand your second question. You should establish a spray schedule based on the disease pressure in your area and different growth milestones, starting when the shoots are 1/2 - 1” long and taking into account bloom, bunch closure, etc. I modified a chart that Virginia Tech put together.
The more I learn about how grapes develop ontogenic resistance to the diseases that are the most troublesome in my area, the more I think I can stop spraying the clusters well in advance of harvest, but the leaves will still need to be protected so they are around to ripen the grapes and store energy for the dormant season.

Your grapes look great, by the way!

 

[kartracer088]

Thanks for sharing you chart. We had a late freeze in Mid May, lost all chutes, and the vines started over with new chutes. So it looks like my vines are 5 or 6 weeks behind yours. I would be interested in hearing when you are able to harvest your marquette grapes. I have kept good records this year of the progress of the growth and the spray dates. So hoping to get a better understanding of the timing.

I don't really have an good records from last year. The Japanese beetles and bunch rot and birds wiped them out last year. The grapes weren't any larger than pees, nothing worth harvesting. This is the third year for the vines and the grape fruit size looks more like the wine grapes I have seen at a local vineyard.

 

[Cynewulf]

I actually harvested the Marquette last Monday, July 27 at 23 Brix and 2.81 pH. It would have been nice to harvest at a higher pH but I was starting to see bugs going after them, some bird damage and shriveling berries, and we had a lot of storms forecast so I pulled the trigger. There don’t seem to be a ton of people growing Marquette in Virginia but the few I know of seem to harvest around this time/early August. I’ll be interested in how they do next year as this was only their second season so I only let a few clusters ripen to see what would happen: 3.5 lbs from 17 vines. I just crushed them and put them in the freezer to toss in with my Cabernet Franc when it’s ripe (only just now starting veraison). Next year I should have more of everything and hopefully a pH above 3 as well. I’d like to try a semi-carbonic maceration next year to help with the acid and pH. Look forward to hearing how yours goes.

 

[kartracer088]

I'll be sure to update this thread when I get that point. Thanks.

 

[tom6922]

I’m growing Marquette/Traminette/Seyval near Ann Arbor, MI. I use mancozeb for the first 3-4 sprays, stopping around June 20 (to stay well clear of the 66 day PHI). I then do 1 or 2 sprays of Immunox, then 1 or 2 sprays of captan (fewer sprays if rain is low and I can stretch them out). You have to limit Immunox use to prevent future disease resistance. By late-July I switch to Serenade (organic) and only use this until after harvest. I always get powdery mildew on Marquette in the fall, and treat that with sulfur or stylet oil. Marquette is ready to pick usually between Sept 5-12, depending on the GDD (heat days). I have to net them as soon as veraison starts to prevent bird loss (they will find any gap in the net!!). If I leave them longer, the wasp activity really picks up and they damage the crop.

 

[VinesnBines]

Is the Marquette very sensitive to sulfur spray? I have Foch and Chambourcin that are highly sensitive so I’m trying to figure out a good powdery mildew PM spray for them. How good is Imunonex for PM?

 

[Cynewulf]

I specifically chose to plant Marquette because it’s not supposed to be sensitive to sulfur and I’ve had no problems. Myclobutanil (Immunox) is very effective against PM: https://plantpathology.ca.uky.edu/files/ppfs-fr-s-18.pdf, though you are limited to 5 applications/season.

 

[tom6922]

I have used it without a problem, but I mostly have used the oil instead. I believe AA says that Marquette is slightly sensitive to sulfur. Immunox says it treats PM, but I have not used it for that. Keeping an open canopy that can dry quickly helps.

 

[VinesnBines]

Thanks! Some of my vines are in second leaf and I’ve dodged PM so far but I know I’m on borrowed time!

 

[kartracer088]

Getting back to this thread to report on the harvesting of the Marquette. I have 7 vines on their 4th year. This is the first year I was diligent on the Spray program and the 1st year there were any grapes worth picking

I have been watching the brix. I would pick 6 or so grapes from random bunches, and the day I harvested, they ranged from 20 to 26. I was getting a little concerned, seeing flies eating in the grapes and some bunches with shriveled grapes. See attached picture. So I went ahead and picked them. Got 17 lbs from the seven vines. I think it would have had more of we hadn't had the hard freeze in May this year. From what I have read, should be getting around 6lbs per vine. Hopefully next year will be better. Probably should have waited a while longer before picking, but was concerned about losing more grapes and rain that was predicted over the next couple of weeks. I will be lucky to get a gallon of wine out of it.

After destemming and crushing
Brix from refractometer = 23.9
pH=3.0
TA=13.8

The must has been fermenting on RC-212 yeast for 4 days. Guessing I will need to do some acid correction later.

Planning on doing malalactic fermentation with Whitelabs WLP675 and cold stabilization. Open to suggestions.

Can someone identify what is going on with the shriveled up grapes?

 

[tom6922]

Guessing they got missed by a spray and got infected with something. Does not look like black rot to me, but it could be. I get a few of those every year. I think you were correct to pick, waiting too long for the perfect time usually results in too much wasp and fly damage for me. My numbers this year are similar to yours. I always reduce acidity right away with calcium carbonate, prior to fermentation or adding sulfite. You want to get the ph closer to 3.3 for malolactic to work.

 

[BigH]

After destemming and crushing
Brix from refractometer = 23.9
pH=3.0
TA=13.8

Those numbers are not bad for Marquette in a hot summer. It would have been nice to get the TA down another couple points, but I don't think you had that option.

In the future, you can use a malolactic metabolizing yeast like 71B to chew up 30-40% of your malic acid. That will increase the pH to a level that will be more hospitable for MLF. Skin contact time will also bring the pH up. You will probably come out of fermentation around 3.2

H

 

[kartracer088]

Update on Marquette
Picked on September 2nd, started fermentation on the 3rd.
After 6 days of fermentation:

SG = 0.992
pH = 3.28
TA = 1.5 ( actually went up a little)

I saw the comment on using the 71B yeast, and I think I actually have some in my freezer, but I had already used the RC212

So my question is, should I leave it on the skins longer? the MLB I have says it will work down to pH of 3.1.

Should I press it before adding MLB?


On the topic of fungicide and insecticide spray before harvest, the last fungicide I sprayed was Spectracide Immunox the 1st week of August, and Sevin a week after that.

Should I have been applying any other fungicide up to before harvest?

I wasn't really seeing any insects through August, up until just before picking, and then it was just a few flies and I did see one yellow jacket.

Thanks for the feedback, this is my 4th year into wine making and I still have a lot to learn, but is a lot of fun. I just ordered 25 more Marquette vines from Double A Vineyards. With that in a few years, I should be able to get a couple carboys of wine a year going.

 

[BigH]

pH = 3.28
So my question is, should I leave it on the skins longer? the MLB I have says it will work down to pH of 3.1.

I have had good luck with the MBR31 strain with pH above 3.2. You have probably gotten all the pH shift you are going to see from the skins, but I could be wrong. I think you will be fine. Use MLB nutrients if you are concerned.

Should I press it before adding MLB?

Some yeasts can coexist with an active MLF. I think 212 is one of those, but look it up to be sure. The Scotts Lab Fermentation Handbook is a good place to go for this info. I added MLB to a couple of my musts last year for the first time (frontenac and petite pearl). It worked fine. I was worried that pressing might interrupt things, but it did not. Disclaimer: not much of an expert on this topic (nor any of the others really)

Should I have been applying any other fungicide up to before harvest?

It depends on the variety. Some of them get downy mildew late in the season, like La Crescent. You start running out of choices the closer you get to harvest. Captan isn't a great fungicide compared to the others, but it has a really short PHI and it does control Downy. Tight cluster varieties may need treatment for botrytis, but that needs to happen at bloom I think. If powdery mildew is a problem, try to time an application with an effective fungicide a few weeks out that satisfies the PHI. My marquette has not shown very many late season fungal problems.

Note that a spray after harvest may be warranted to keep enough green to harden off the shoots. You can switch back to mancozeb for this if you want.

H

 

[wood1954]

I have found that you can add up to 4 grams of potassium bicarbonate per gallon of wine and you won’t taste it. Start at 1 gram per gallon and test after a few hours. I alway add before pitching yeast. It foams a lot.