Thinning of vertical shoots

In the "New World" this is true.

The french also say that "Wine is made on the vine"

I repeat: I am talking about a trial between rows in the same year!!! Not one year compared to another. Also, the crop is not yet in for this year. A vigorous vine does not mean the fruit is go

In my vineyard(s) I have a sandy loam. There are a variety of soil types in Maryland. It is NOT THE SOIL that promotes the vigor here. It is the moisture we receive. I believe the same is true in Michael's case. The better years are the years that we have minimal rains during bloom and fruit set and then again minimal rain after verasion.

You refuse to mention were you are growing your grapes so I assume you are in California which in most cases never or very seldom experiences this situation. If this is the case, you can not even begin to get an idea of the vigor problem without first hand experience.

Grapes can be grown on a variety of soil types. I suggest you read the book "Terroir" by James E. Wilson. Wilson, like myself, is a Geologist. All of my professional career was working as a Geologist, Hydrologist and Physical Scientist. I worked for a vineyard and winemaking consultant after retiring.

Just curious, what is your background?

Hi:

Hate to interupt this interesting pissing match. But wood chips are not likely the 'natural' mulch for vines. What would be, is what comes off the vines themselves plus any additional material from the support in a natural condition.

I and SWMBO have never seen a wild grape in a conifer, though it may occur. But I have seen plenty in hardwoods. So based on observation a natural mulch would consist of grape leaves, canes, rotten grapes and leaves from the host support.

I would be very careful with chips. Conifers and all of their by products tend to acidic, hardwoods to basic. So if one is to use other than grape by products for mulch then hardwoods might be the best source. Grape by products and hardwood leaves would more likely be much better than chips.

In addition because conifers grow in generally tough conditions, ie drought during the growing season they produce chemicals that inhibit growth of other plants to reduce competition for soil nutrients, water and sunlight.

Also I think the real benefit from mulch is the longterm incorporation of organics in the soils which promote water, nutrient holding capacity and better biotics for bugs, fungi and bacteria that can contribute to over all health of the vineyard.

Most backyard vineyards around here grow grass right up to the vine trunks. Grass clippings are left in the vineyard along with leaves. Some chip the prunings while others pile and burn. No one I know uses chips. So dry farm, others irrigate, that is soild water capacity dependent. I see no issues with this in the health of the plant or the grape nor any need to mulch.

Lastly the struggle arguement has traction for a good reason. Fruit is smaller making skin to juice ratios better for hearty reds. In addition ripening can and usually does occur sooner with the obvious advatages.

Just my $0.02

Steve Oregon

Thanks Steve

I have used pommace in the past in my vineyard. I have quit doing so recently because I have a problem with racoons. I have to live trap and transport and release them. If I did not have the racoon problem, I would continue to use pommace around my vines. Of course they might get mad grape disease from eating their own :-)

In Michael's case, if he thinks mulching is beneficial, a refelective mulch may benefit because what he seems to need in the Great Britain climate is more sunlight. I know there are reflective plastics made but they are a PITA to secure and fairly costly.

doublsb's comment that growing degree days and sunlight are not the major factors contributing to brix levels, is in my opinion, showing a major lack of understand on viticulture.

You live in a very beautiful state. In what part do you live? We vacationed in Oregon several years ago and it was one of our most enjoyable vacations ever.

Paul

There is no question that mulch helps maintain a consistent soil moisture. Most parts of the country don't get rain as consistently as Maryland apparently does. It may come a flood and then not rain for a month in a lot of places, while 90+ degrees. Mulch will reduce the need to use water for irrigation (very important in some places).

I would not use wood chips of any kind unless they had been through a compost cycle. The best mulches IMO are hay or wheat/rye/oat straw. Those may not be cost effective to obtain on a large scale unless you grow your own. Leaving grape clippings or pomace in the vineyard as mulch is not a good idea because you are leaving disease sources to spread infections. If you had black rot or mildew on your grapes, you need to get rid of as much of the infected tissue as you can that will serve as a ready disease source the next year. Especially if you aren't into spraying a lot, it would be better to rake all fallen leaves and dispose of them away from the vineyard. The custom of returning pomace to the vineyard has been associated with the spread of leaf roll virus and is no longer recommended in many places.

The only negative that I have seen associated with mulch in general is that it can provide hiding places for some pest larvae (and mice, etc.). I would have to do some research to find it again, but I believe that some recommend raking mulch away to expose bare ground for a time and then recovering later so as to disrupt the life cycle of the particular insect pest.

Stephen

I can see the possible benefit in such places. However, the original poster, Michael. lives in England and although I have not lived there, I believe the conditions you mentioned probably are not what he experiences on a yearly basis.

Maryland occasionally has some drought periods but not lengthy and not severe enough to effect grape vines; lawns and gardens, yes, but usually not grape vines. Typically in the region, water is used in the first year and after that none or very sparingly with drip irrigation. Most use no water at all. There are ways of determining drought stress in vines, such as looking at the position of the tendrils near the shoot tips.

One of the possible negatives I can see in mulching in areas such as the Mid Atlantic and possibly England is that near surface soil moisture promotes shallow roots and discourgages deep rooting. If deep rooting is encouraged, the roots find their source of moisture and nutrients. If shallow roots are the mainstay of the vine, then when droughts do occur, it is possible that the vine can be affected more because of lack of deep roots.

That is good information. I have read that immature mulch in the decomposition process can actually rob nutrients instead of adding.

Thanks for that information. It is a good thing that I have not been doing it the last several years.

I am very careful to rack my vineyard thoroughly in the spring.

As I stated previously, I also think it is good practice to spray fungicides AFTER the harvest until leaf fall to reduce the innoculum prior to next spring's budbreak.

I think that perhaps, depending on the mulch, it can lower soil temperature which may not be in the best interest of the vine. It may also, again depending on the material, reduce the reflectivity of the light under the canopy.

I hope Michael does some controlled experiments by mulching some rows and not others on a yearly basis and gives us feedback on his results.

I don't know if mulch has any negative affects on deep rooting or not. It certainly would have less impact in that way than using drip irrigation on bare ground. If you lost your ability to irrigate, then you would be in trouble.

That is a good idea for Michael to do experiments. Michael's limestone soil may be the key to his vines doing as well as they do without mulch. Permeable limestone allows the roots to penetrate deeply to reach subsurface water. If the species/rootstock used is compatible with limey soils, this is a major factor. That is the only way the French get away with the haphazard way they grow grapes. Many soils may not allow root penetration, no matter which variety is being grown. Most hybrids with American species do not like high pH soils, unless on specially selected rootstocks.

Stephen

I have not toured French vineyards. What is the haphazard way they grow grapes? Not disputing what you say, just curious.

In my limited experience with hybrids, it is better to grow them on rootstock. I know, for example that Chambourcin self rooted is much less drought tolerant than those on rootstock. The self rooted ones do not develop a deep root system.

I haven't been there personally, but apparently some plant them somewhat randomly at high density (no distinct rows) and on steep hillsides with no irrigation.

Paul

Southern part of the state, the Rogue Valley. Lots of different kind of landscapes here, not quite as varied as Calif. but plenty to see in Oregon for sure.

Tale Care,

Steve Oregon

If a vineyard is grassed up then leaving the clippings is muching with hay. You ARE growning your own!

In the short run I have no doubt you are quite correct. My comments though were specifically what is likely the natural mulch for a grape.

Regarding mildew we do have powdery mildew here. It overwinters in the buds and is distributed at bud break.

I'm an old forester never have been a farmer. I guess I look at the grapes differently. How do I allow a situation, a micro biome that my non-native vinifera can survive. I don't feel the need to whip them in to submission by worry and tinker. A little diesease a few bugs don't make me panic as long as my footprints say the survivability of the plant is not in jepordy. That is a long term objective, like growing trees. If the problem is big then the reaction is big. But the objective is to allow a place where the alien vinifera can be sustained. A truly different perspective than creating a controled environment in which the grapes can be free from harm.

Maybe if I was doing this for a living instead of a hobby I would act more conservatively. Adhearing to what is universal and avoiding that which /might/ be detrimental. But, each vineyard has it's own personality and demons and the viticulturist must deal with each as they come.

Will I screw up, I'm counting on it. But until the grapes tell me it's a mistake here in the vineyard I /have/ to leave grape mulch under the grape plants. Because, that is naturally what grapes do (most plants for that matter), to capture their place in the landscape.

I think high density is common but they are cropped so that they do not yield that much fruit per vine. This is to increase competition between vines. I think that usually the yield is kept to what converts to be about

3 tons per acre or somewhat less in our units of measurement. I also think head pruning is still common in some areas over there so one would not necessarily need "rows" with trellising wires.

There is a trend here in the Mid Atlantic area to grow on close spacing - about 3 feet between vines and cane prune.

That is a VERY beautiful area. I visited that area. You are very fortunate to be living there.