Field grafted vines question

Has anyone ever run across information on the impact to the final product of field grafting over to a new grape variety? There is plenty of available information on the impact rootstocks, clones, trellis type, vine spacing, irrigation, and just about everything else I can think of but my limited searches have so far turned up nothing on the impacts of grafting over existing vines to something new. In a field where it seems that everything makes an impact I find it hard to believe that if one takes a Chenin Blanc vineyard and grafts it over to Syrah that those Syrah grapes will not taste different than ones that are grafted directly to the same rootstock. Should the portion of the Chenin Blanc that is retained impact the final quality in any way?

Has anyone ever run across information on the impact to the final product of field grafting over to a new grape variety? There is plenty of available information on the impact rootstocks, clones, trellis type, vine spacing, irrigation, and just about everything else I can think of but my limited searches have so far turned up nothing on the impacts of grafting over existing vines to something new. In a field where it seems that everything makes an impact I find it hard to believe that if one takes a Chenin Blanc vineyard and grafts it over to Syrah that those Syrah grapes will not taste different than ones that are grafted directly to the same rootstock. Should the portion of the Chenin Blanc that is retained impact the final quality in any way?

Great question, Brian. As usual..I'm totally clueless.
On a related tangent....there's a vnyd down in the CienegaVlly in which a Zin vnyd, planted in the early 1900's, was field grafted over to Viognier. It is advertised as the only "old vine" Viognier vnyd in Calif. Hmmmmm?? It would be interesting how that wine tastes beside one planted in the same sight from young/grafted vines. Those such experiments are not ever done, to my knowledge.
In your example, I would doubt that the CheninBlanc that exists between the rootstock graft and the Syrah shoot...the trunk of the vine...would have little effect on the resulting Syrah wine. I think the root system would have a bigger impact. But I'm just talking like an expert on a subject I know absolutely nothing about..standard modus operandi for us LosAlamos types. Sometimes we just even make stuff up!!
Tom

If you removed the Chenin Blanc vines from the rootstocks, then the fact that they used to be there would make no difference to the Syrah. Whatever characteristics the Syrah grapes have is strictly due to the rootstock and the Syrah vines. Home orchardists have long grown trees that have multiple varieties - say 5 apples - grafted onto one rootstock, and the resulting fruit stays true to its variety.

If you removed the Chenin Blanc vines from the rootstocks, then the fact that they used to be there would make no difference to the Syrah. Whatever characteristics the Syrah grapes have is strictly due to the rootstock and the Syrah vines. Home orchardists have long grown trees that have multiple varieties - say 5 apples - grafted onto one rootstock, and the resulting fruit stays true to its variety.

The way I understand field grafting there would still be some of the Chenin Blanc vine remaining. The rootstock to Chenin Blanc graft is usually a couple of inches above the soil. The grafting over to Syrah usually happens just below the fruiting wire so depending upon the height of that wire one could have a few feet of Chenin Blanc vine between the Syrah and the rootstock.

In that case, I suppose there could be some contribution by the Chenin vine, but I'd think the only way to test it would be to grow vines side-by-side: one Syrah grafted directly onto a rootstock, and one Syrah field-grafted onto Chenin which is on the same rootstock variety. Then test the resulting fruit for differences.

Hi Brian,
Would you consider field grafting just below the fruiting wire “top-working”?

Salute

Brian,
In 1999 or 2000 we grafted two blocks over and it worked out great for us. We brought in a very experienced crew from california and our percentage of success was terrific at about 99%. We had some chardonnay that we converted to pinot noir and muller thurgau. The time for a full crop was far less than re-planting, plus I had the benefit of 20+ year old roots. The hardest part was when I got there early on and heard the chain saws and could see the tops of my vines laying all over the ground ( a bit scary ).
As far as the rootstock impacting anything on the grapes, we saw nothing but what we had grafted to.
Cheers !
Linda

There has been much discussion in the past about the difference between grafted and ungrafted vines with opinions on all sides. I'm not sure there's any reason to believe that the effects of field-grafting would be any different than normal bench-grafting. The only difference would be the length of the host vine - a foot or two or three as opposed to inches. Of course, in many cases then you'd have two "hosts" - the rootstock and the "trunkstock" (to coin a term). Between those two, I'd have to think that the rootstock would still be far more important, with the trunk serving as little more than a conduit for nutrients. My guess is the behavior of the vine and quality of fruit would be little different than if the new variety were bench-grafted to the rootstock, with very little effect from the original grafted variety.

We had some chardonnay that we converted to pinot noir and muller thurgau.

I'm very interested in why you chose Muller Thurgau. It is not a variety that has many fans.