It looks like Bacterial wilt to me. I would pour a gallon or two of a 10% bleach solution in that spot and leave it for a while before replanting there. It should be okay to use that spot again in a few weeks if that is what it is.
I like the Estamino root stock but it doesn't have resistance to Bacterial wilt in my experience. The only root stock that I know that is resistant to BW is RST-04-106-T. I now use it on most of my plants and in three years have not had a single plant fall to BW that was grafted onto that root stock. In the past I had at least a few plants and sometimes more fall to it every year especially after a good rainy spell when it was hot.
You can cut a main stem off of the wilted plant and put it in a glass of water and if a white milky substance oozes out into the water from where the stem is cut then it is Bacterial wilt.
Bill
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