Dry farming grapes

This year I tried a "dry" garden for the first time. Some of my grapes are along the edge of this area, so they of necessity weren't watered either.

There are four plants in this area, one of them a concord/interlaken seedling which was close to another tree that I did water. It was harvested earlier in the season. The other three are concord. They are approximately 30 to 40 years old and in previous years have been deeply watered once a week.

I started harvesting this morning. I've been smelling the grapes for weeks, and they smell like candy. :) I wish I could bottle that smell. The following picture is the harvest from about a 5 foot section of the vines. There is a problem with the next section but I'm not sure what it is yet. Looks like herbicide damage, but it's right in the middle so that's unlikely. The leaves are dying and the grapes drying up without maturing. It's possible that it's drought stress, but the harvest below was from the rest of the same vine so I'm still thinking about that one.

The harvest appears to be approximately equivalent to previous years, the grapes perhaps slightly smaller. The grapes are sweet, right off the vine. I'll be juicing them today and provide an update.

I read this week about an old herbicide which has come back into use due to the resistance of weeds to the glyphosate-based herbicides.

Monsanto/Bayer has developed new GMO strains that allow the use of this older herbicide (I forget the name).
This older herbicide has the potential of evaporating easily, and an errant breeze could have wafted the fumes over your grapes in an uneven pattern.

Where are the grape vines located? Are there any GMO crops nearby? What are the potential wind vectors in that area?

I assume that there are other potential vectors that could be affecting your plants: soil, insects, microbial infections come to mind.

Is it possible that the grapevine has been physically damaged somehow?

Do the symptoms appear on different parts of the same grapevine, or is the damage confined to individual plants?

Just some avenues for investigation. Hope the questions help.

Mark, the grape vines are between two houses, each about fifteen feet away, and primarily blocked from the prevailing winds. The piece affected is in the middle, about halfway down the row. It may easily be physical damage, but it's only affecting one area of the plant and the vines that go beyond that area are fine. It may be herbicide drift, but the area is suburban so I'm not sure where it would come from. The neighbors used to spray in that yard, but they moved out a year ago. It's entirely restricted to one area of one grapevine, the rest seems fine.

I would think that a systemic herbicide would affect entire plants, but I'm not an expert on that. You may have some runoff from the previous year's spraying that has affected only a single grapevine.

Do I understand you correctly to say that the ends of the vines from the same rootstock plant are unaffected?

The photos do not show close-ups views of the actual vines. There could be some invasive, but hard to see insect involved. See if you can trace the vine back from the damage back to the roots of the vine to see if there is any sign of an insect or even damage to the bark of the vine. Some pests do their damage under the bark of the vine. Look for evidence of boring and egg-laying by insects. Even bits of sawdust can be an indicator.

Perhaps you could find a local master gardener with experience with grapevines to take a look.

The main vine is unaffected, and there are ripe grapes and no damage on vines beyond. If an herbicide just lands on the leaves it can sometimes affect just that piece of the plant--I ran into something similar last year, where I think one of my neighbors had been spraying and it affected only a piece of one plant. With grapes being so hardy, it usually takes much more than a drift to affect them.

The master gardener is a good thought. I see hornets and other insects eating the fruit, no sign of bark damage, eggs, or frass. I do wonder however (now that you've brought up the possibility) whether the former neighbors might have dumped something on that side of the yard when they moved.

For the purposes of this post I'm not really concerned, except as it might be related to the lack of irrigation. I don't think it is, but it's possible. I'll have to take a closer look after I prune and see if I can trace the cause.

Have you checked for root damage from burrowing animals, such as voles?

It would be a longshot since I would think if there was something eating the roots, or something in the soil, it would be affecting the entire plant.

Without seeing the damage myself, I would suspect some sort of overspray.

Good luck in solving your garden mystery. As I recall, I'm told that hot summers make for sweet grapes, but a lower quantity. Your harvest looks pretty good.

Mark Kissinger wrote:Have you checked for root damage from burrowing animals, such as voles?

It would be a longshot since I would think if there was something eating the roots, or something in the soil, it would be affecting the entire plant.

I haven't, and we do have gophers. I can't really see at the moment--too much leaf in the way--but sometimes that happens. Certain feeder roots affect certain parts of the tree (or vine, in this case) which is why half of a tree might die while the other half is apparently fine. I think it's overspray too, but if a gopher got a major root or something else partially girdled the trunk, it could kill only part of the vine. Under those circumstances the vine could easily put all its energy into the new growth, letting the older growth die.

My grape vines sometimes suffer the same issue. The dieback and/or wilted fruit could be due to a number of things:

1. Damaged or weak vine/leader/roots
2. bird/flying fox damage
3. Insect damage to fruit - bees, wasps, etc
4. inadequate air flow promoting fungal attack
5. Sunburn

Given the circumstances and descriptions, it could be a bit of fruit damage by insects/birds, combining with inadequate air flow causing fungal attack.

If you see wilting bunches or part bunches of grapes it's best to snip them off early to avoid spreading the problem.

Grape vines are pretty hardy.

Also, it's counterproductive to irrigate grapes in MOST circumstances - there will be a higher yield but a loss of flavour and watery fruit. Dry season grapes always produce better tasting, smaller fruit, also true for winemaking.

F Agricola wrote:It's counterproductive to irrigate grapes in MOST circumstances - there will be a higher yield but a loss of flavour and watery fruit. Dry season grapes always produce better tasting, smaller fruit, also true for winemaking.

I'd heard that, but mostly from areas that have at least some summer rain. So I wanted to try for myself and see how it works in an area with no summer rain.

If you make wine, let us all know how your experiment worked!

This year I tried a "dry" garden for the first time. Some of my grapes are along the edge of this area, so they of necessity weren't watered either.

Lauren, those grapes are beautiful!
I don't know anything about the damage but I have always heard that grapes/muscadines need good winter moisture to bear well the next summer.  Dry summers were good as they produced less fungus and mildew.  This was our experience with muscadines that we cultivated in the wild.  We never watered at all and could tell  in the years when we had good winter rains that they produced better.

Judith Browning wrote:

I don't know anything about the damage but I have always heard that grapes/muscadines need good winter moisture to bear well the next summer.  Dry summers were good as they produced less fungus and mildew.  This was our experience with muscadines that we cultivated in the wild.  We never watered at all and could tell  in the years when we had good winter rains that they produced better.

We generally get the majority of our moisture during the winter in the form of snow. I can tell you I won't be (deliberately) watering the grapes from now on! This is just one set--the others are in sprinkler and drip areas, which will be changed as I transition the yard to use less water.

Mark Kissinger wrote:If you make wine, let us all know how your experiment worked!

Not wine, but I finished juicing them yesterday. The juice tastes basically the same, perhaps slightly more concentrated, but I got only four quart bottles from every juicer batch instead of six as I got last year. So apparently the grapes are drier, which is totally expected. The whole house smelled like grape candy for two days. :)

Lauren Ritz wrote:Mark, the grape vines are between two houses, each about fifteen feet away, and primarily blocked from the prevailing winds. The piece affected is in the middle, about halfway down the row. It may easily be physical damage, but it's only affecting one area of the plant and the vines that go beyond that area are fine. It may be herbicide drift, but the area is suburban so I'm not sure where it would come from. The neighbors used to spray in that yard, but they moved out a year ago. It's entirely restricted to one area of one grapevine, the rest seems fine.

The damage of grapes looks like sunburn. The grapes are exposed tu direct sun..

Thanks, Lauren.

I learn so much from other people on this forum. I never got to see the grapes I planted come to fruition. Had to move away when my Dad died.

That was a beautiful harvest. Wow.

About the troublesome grapes, I think F Agricola was on the right track with the fungal suggestion. I suggest investigating black rot.

https://grapesandwine.cals.cornell.edu/newsletters/appellation-cornell/2014-newsletters/issue-17/managing-black-rot/

If it is black rot, the normal fungicide used is called Bordeaux Mix, which is just a mixture of copper sulphate and lime.

But it needs to be used in conjunction with good vine and surrounding area hygiene, and used infrequently and strategically.

F Agricola wrote:If it is black rot, the normal fungicide used is called Bordeaux Mix, which is just a mixture of copper sulphate and lime.

But it needs to be used in conjunction with good vine and surrounding area hygiene, and used infrequently and strategically.

I don't use any kind of 'cides,' but thank you for the information. Our year has actually been exceptionally dry and these grapes weren't watered at all, so humidity shouldn't have been an issue, but I'll keep an eye on it. Thanks!

Joylynn Hardesty wrote:That was a beautiful harvest. Wow.

About the troublesome grapes, I think F Agricola was on the right track with the fungal suggestion. I suggest investigating black rot.

https://grapesandwine.cals.cornell.edu/newsletters/appellation-cornell/2014-newsletters/issue-17/managing-black-rot/

That's an excellent reference site, and it does look like what happened to the grapes. I'm not certain though, because humidity has remained pretty low in this area. I'll keep an eye on it.

Utah has a relatively high altitude and may be subject to heavy dews which could be a factor in promoting the fungus. Especially if there are not enough drying winds to keep the moisture at bay.

I am not an expert, but only try to think of potential vectors that could be involved.

It may not help with this year's crop, but you might consider how much pruning is done to the lower parts of the vines. What sort of fall pruning do you do?

Just throwing out possibilities here.

Mark Kissinger wrote:You might consider how much pruning is done to the lower parts of the vines. What sort of fall pruning do you do?

Just throwing out possibilities here.

The vines are pruned back to primary runners each fall. Everything else is new growth.

This picture is actually the interlaken rather than the concord, but it's the same idea.

Thanks for the reply.

Have you come up with a hypothesis about what to do next?

I've found this whole discussion to be very informative. There is a wealth of information in the brains of people who visit this site.

Mark Kissinger wrote:Thanks for the reply.

Have you come up with a hypothesis about what to do next?

I'll be pruning this section separately--anything that comes off it will go into the buried compost pit rather than allowed to compost on the surface. Normally I just allow the leaves to fall to form compost and mulch for the grapes. We did find a hornet nest buried in this section, and I haven't seen any hornets around for weeks, so that's likely part of the grape problem. Free buffet! I'll keep an eye on the grapes next year. None of the damaged leaves have that black bubbled surface mentioned in the black rot post linked above, and now that I know what to look for I'll keep an eye out for it next spring. Apparently the dried up grapes that fall or are left on the vine are breeding factories for the fungus and explode in early spring, releasing the spores. I'll make sure there are no dropped grapes on the surface and that should help as well. If the spores can't spread, they can't infect anything.

It is really hard to say what was the real problem with your grapes, but sunburn or water defficiency (or both) seems the most probable to me according to your pictures. If they were watered heavily in last years (as you write) and this year suddenly you stopped, drought might be the reason. Your vines have shallow root system, dependent on watering..

I have my own vineyard ( app. 800 sq. meters, 700 grape vines), trying to do it in "permaculture way" and some grapes were also damaged by water insufficiency this year (this summer was one of the the hottest and driest in last decades..). The vines are only several years old, watered only in the first year and don´t have their root system deep enough yet. This years drought made some clusters to dry up completely. I explained it to myself that the plant "sacrifices" the berries to save its life..

Jan Hrbek,

Nice goose run nestled in between your vines. I assume that their manure "feeds" the grapes? Have you employed any rainwater harvesting techniques to help make rainwater more accessible to the grapes? How much of you grape harvests do the geese manage to get at thru the chain link fencing?

If so, since too much water reduces the flavor of the grapes, how do you control the amount of rainwater "irrigation" that the grapes receive?

Jan Hrbek wrote:It is really hard to say what was the real problem with your grapes, but sunburn or water deficiency (or both) seems the most probable to me according to your pictures. If they were watered heavily in last years (as you write) and this year suddenly you stopped, drought might be the reason. Your vines have shallow root system, dependent on watering.

That's possible, certainly. Up until last year they were watered deeply once a week, so the majority of the roots should be deep enough to avoid that. The vines themselves are between 30 and 40 years old.

I brought the geese to the vineyard to graze the grass (Elymus repens - "couch grass") in between the rows. It was the first intention. I just decided to stop using petrol engine mower (noise, carbon footprint etc..) Fertilization of the vineyard by geese is bonus..  Meat is the second bonus.. I had them free-range in spring, but they started to damage the trunks (stripped the bark..), so I had to start using this fencing. It is 10 meters long, 1 meter wide. I move it every day.. They have access to fresh grass every day. The wire mesh is quite dense, they can not get to the grapes..

Your second question: I do not do any "rainwater harvesting". I only mulch the row of vines by straw, grass clippings, leaves and hay.. To keep the soil beneath the vines moist.. We have some 500-600 mm of rainwater / year in our area. I used irrigation only in the first year after planting. Then the vine must take care of itself on its own.. by sending the roots to the deep soil.. I don´t control the ammount of water for the vines, but it is possible. If you want to reduce the accesibility of water to the vines, you let the vegetation inbetween the rows grow tall. The tall vegetation evaporate quite large ammout of soil humidity.. If it is drought, you must keep the vegetation as low as possible.. This is the only water control possible in organic /permaculture vineyard. Of course it is possible for me to irrigate my vineyard to have bigger harvest of the grapes, but I don´t want to.. The quality of the grapes / and wine../ is much worse then..