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Electrojim

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I'm in Orange County, CA, with plenty of hot days, and inland far enough that there's not much fog aside from the morning high-elevation 'June Gloom' that doesn'tget anything wet. Seems like a good grape-growing area, and the Concord vine I've had for more than 20 years grows like a weed, giving me plenty of juice for grape jelly.

My single Zinfandel vine is now several years old, and I was finally looking forward to a small, yet good crop this year... maybe enough to make a few bottles. The clusters are full and tight, although some of the grapes appear to be maturing (turning purple) far too early. Here's a shot of part of the vine.

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Taken from another viewpoint, you can see my problem:

100_0947.JPG

It appears that those early-maturing grapes are turning to raisins, or simply drying out, before my very eyes. I have had this same issue on this vine since it started prducing a few years ago, but there weren't enough grapes to do much with anyway. Yet I did ask for help here before, and one member diagnosed this as a fungus. So this season I've been spraying religiously, every couple of weeks, with a copper sulfate spray and 'spray spreader' (wetting agent) mixture, starting before clusters formed.

This is really disconcerting, and I'm at the point of giving up on this vine and replacing it with something else, but would certainly like to know what's going on. I'm wondering if another variety might be more robust and a better choice. All comments and recommendations are very welcome, and I thank you all in advance.
 
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Zinfandel is prone to millerandage, which is uneven veraison you are seeing. You have a wine grape that requires vine management. You should be dropping lagging clusters and managing the growth habit of the canes because Zinfandel tends to overproduce. If not, then you will have clusters in several stages of ripeness, and even clusters that will not ripen. Try training your vine to the cordon and spur shape to help limit fruit and spread it out. You will also want to try deficit irrigation to slow berry growth which will help even the ripeness

My guess is that the cluster you show is simply raisining, not rot, since you are in dry Orange county. Raisins are not going to ruin the wine if you can still get most of the cluster to ripeness.
 
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VinesnBines

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From my (very) limited experience, raisins don't hurt. I know a winemaker that let his Barbera dry in a greenhouse for several day to get the brix to 30 -35. Keep the course and keep us posted.
 

Electrojim

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From my (very) limited experience, raisins don't hurt. I know a winemaker that let his Barbera dry in a greenhouse for several day to get the brix to 30 -35. Keep the course and keep us posted.
Will do. BUT... if last year was any indication, I'll have 'not raisins,' really, but dry, crispy grape skeletons by the time Mr. Brix breaks 10 on the few berries that survive. I'll keep us all posted. Many thanks to all for the info.
 

Obbnw

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Looks like you may have some powdery mildew on the grapes. I had powdery mildew on my grapes one year, barely noticed it on the leaves.

Mine had a similar look and weird ripening.
 

vtoddw

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I've got some 6 year old Zinfandel vines here in Murrieta, CA, a few miles away from you. I've had similar issues every year with them, my understanding echoes what Snafflebit said that Zinfandel is difficult to grow due to the issues it is prone to. I have an equal amount of Merlot and Cab Sauvignon vines which tend to produce a more stable crop. The last two summers in a row I've harvested my Zin after labor day weekend in September because we had 112 F the entire 3 day weekend, two years in a row now. The vines were already looking stressed with leaf burning and reddening, plus a lot of raisining.

I have recently learned what VinesnBines also just repeated, which is that raisins aren't garbage, you can actually use them to boost your sugar levels, color and tannin, so shriveled grapes does not mean a totally lost crop. Obviously you'll need enough liquid to make a wine, so hopefully we'll both get enough healthy berries this year to avoid adding water, but depending on the yield you may not notice the water at all.

On a side note, my 6 year old Zinfandel vines are cordon trained, which I've heard is not the best for that varietal due to the way it tends to grow. Apparently the ideal structure is Head or Crown trained, where you essentially have a goblet shape of spurs with the fruiting canes all growing out in a 360 degree goblet. I actually planted 6 more Zin vines this year with the intention to head train them and see the difference.

Here are some pics from 3 different zin vines I took over the last couple of weeks:berry shrivel.png sunburn.png healthy cluster.png
 
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I've got some 6 year old Zinfandel vines here in Murrieta, CA, a few miles away from you. I've had similar issues every year with them, my understanding echoes what Snafflebit said that Zinfandel is difficult to grow due to the issues it is prone to. I have an equal amount of Merlot and Cab Sauvignon vines which tend to produce a more stable crop. The last two summers in a row I've harvested my Zin after labor day weekend in September because we had 112 F the entire 3 day weekend, two years in a row now. The vines were already looking stressed with leaf burning and reddening, plus a lot of raisining.

I have recently learned what VinesnBines also just repeated, which is that raisins aren't garbage, you can actually use them to boost your sugar levels, color and tannin, so shriveled grapes does not mean a totally lost crop. Obviously you'll need enough liquid to make a wine, so hopefully we'll both get enough healthy berries this year to avoid adding water, but depending on the yield you may not notice the water at all.

On a side note, my 6 year old Zinfandel vines are cordon trained, which I've heard is not the best for that varietal due to the way it tends to grow. Apparently the ideal structure is Head or Crown trained, where you essentially have a goblet shape of spurs with the fruiting canes all growing out in a 360 degree goblet. I actually planted 6 more Zin vines this year with the intention to head train them and see the difference.

Here are some pics from 3 different zin vines I took over the last couple of weeks:
I noticed that @Electrojim has the vine growing on an arbor, which complicates the issue. That is why I suggest the cordon layout. Head training would be the traditional vine shape, but even that is not used a lot commercially, but I love the look!
 

Electrojim

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Thanks, guys. The good news is that the shriveled berries in my photo are still the only ones that don't look good. Otherwise, nicely-ripening ones and other still green. I'll continue to spray with the copper solution, but an arbor is my only option right now. In fact, these Zins share the arbor with the Concords (which never give trouble... like weeds!), and it's mostly for shade; harvesting the grapes is just an added plus. I'm not an avid winemaker and tend to get discouraged and rely on 'Two Buck Chuck' to ease the pain. If the Zins don't work out in the long run, I'm open to suggestions as to what to replace them with, maybe something that will grow on an arbor and prove more robust here.
 

NorCal

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You have to love those huge Zin clusters! My first thought on the raisened berries was due to early exposure to mildew, but I don't see any staining on the stems.

I was looking over a bin of grapes that a customer was going to pick up and I started picking out the shriveled berries, when the winemaker asked me to stop. He said that a small % gives the wine complexity and his preference is to have some of them.
 

VinesnBines

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When we were harvesting a Petit Verdot crop, the winemaker/vineyard manager said pick everything including the raisins.. I wondered but picked them all.

On the other hand, I have some black rot and read that I should (spray of course) but leave the mummies, they will fall off or if they stay with the cluster at harvest, they won't harm the wine. ?????
 

vtoddw

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When we were harvesting a Petit Verdot crop, the winemaker/vineyard manager said pick everything including the raisins.. I wondered but picked them all.

On the other hand, I have some black rot and read that I should (spray of course) but leave the mummies, they will fall off or if they stay with the cluster at harvest, they won't harm the wine. ?????

This is a really interesting page I read that explains the various reasons for berry shrivel. One thing of note is that grapes are still usable in wine if the berry shrivel is due to bunch rot necrosis, while the other causes tends to make them unusable.

 

VinesnBines

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This is a really interesting page I read that explains the various reasons for berry shrivel. One thing of note is that grapes are still usable in wine if the berry shrivel is due to bunch rot necrosis, while the other causes tends to make them unusable.

I read this article to say just the opposite; that grapes are usable if shrivel is due to sunburn or dehydration, The article says that if the berry shrivel is due to bunch rot necrosis or what they call berry shrivel, the grapes stay sour which implies the grapes may affect the quality of the wine. Frankly, I found the article a little confusing.
 

Joe B.

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I see the same issue on very few of my bunches every year and have no idea why. It is always just a few bunches and on different varieties not just Zinfandel. If I'm doing something wrong I have no idea what it is. My guess is the high temperatures my location experiences 100+ has something to do with it or possibly some kind of pest. The fact it happens well before veraison has always had me puzzled. This is a great discussion the responses defiantly have me thinking.
 

vtoddw

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Correction, I had to reread that article, sorry for the misinformation but apparently BSN makes grapes unusable but sunburn and dehydration will not. Glad you pointed that out, I'd hate to misinform anyone.
 

vtoddw

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I went to a local vineyard last year to harvest cab sauv and cab franc on September 20th where they have enough vines to produce about 2 tons of grapes. I noticed that their berries on the west side of the rows were also mostly shriveled. So it seems that even the pros suffer from the same issue and may not know how to prevent it. Given that it was on the west side, that likely means that the late day sun exposure is the primary factor, which is why it's advised that leaf thinning only be done on the east side. Hopefully that helps, I'm still experimenting every year to figure out a solution as well because I only have 30 vines so every bit counts.
 

VinesnBines

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Correction, I had to reread that article, sorry for the misinformation but apparently BSN makes grapes unusable but sunburn and dehydration will not. Glad you pointed that out, I'd hate to misinform anyone.
That article was confusing. I had to read it a few times to be sure what they were saying.
 

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