All the vine is dead already? And how old may be the visible longitudinal crack and how is oriented (towards north)? And what about neighbouring vines - are they also damaged?
usually, vitis spp roots are more sensitive to frost., thus our farmer add a lot of soils in the base of tree in the autumn. aerial parts can tolerate usual frost( not ultra frost)
This vine is in Australia I presume? Were there other vines similarly affected? Maybe hare damage? Hares strip bark from vines, but usually lower down. There is also a possibility that lightening strike might be involved, but neighbouring vines would also be affected.
Vine growers and consultants sometimes send unusual virus-like symptoms, but the most common viruses are tested negative. Here, is a good platform to share the ideas about them.
The samples were tested negative to 12 viruses. Likewise, mycologists could not find any fungus and the lightening syndrome has been ruled out.
I received the following response from the consultant:
"This is a block of Shiraz on an unknown rootstock in McLaren Flat (South Australia). The area has been salt affected in the past, with neighbouring blocks suffering greatly in seasons past. Virus sampling was conducted earlier in the year and no virus issues were detected in our sample. The rootstocks are dying, which I believe to be the primary cause of the splitting. This untimely death, I believe to be a result of salinity on poorly selected rootstocks. The rapid extreme "drying" has occurred to me in light of salinity issues. I also think that hard pruning has amplified the affect resulting in a quicker death. The block is around 20-25 YO. I believe that about 20-30 vines are affected in an area of 1/4 acre. I have seen this once before in Langhorne Creek (South Australia), but much less seriously.I have not carried out cross sectional cuts. I think that I will though..."
In the end the grower has decided to pull the vines out.
It would be interesting to see what the graft unions are like. I often see poorly formed graft unions that are contaminated with either biotic or abiotc contaminants. Trunk diseases are one possibility, but there could be issues with embedded bidding tape or other problems. It would also be useful to see the tissue in the rootstocks. Have they thought about black foot? It may however, be poor drainage, salt or other toxic elements in the soil.