Any ideas/diagnosis about this wilting?

[Hervey]

First noticed this about four days ago. Little Lucky grafted onto Estamino. Three other nearby plants are so far fine, one of which is likewise grafted onto Estamino.

Last year a Big Beef grafted on Estamino did the exact same thing in the exact same spot! It was the only plant that went down like this. This spot is cursed. Last year I pulled it and split the stem and saw nothing unusual. But I am new at this. Last year it did not respond to more water.

I have 30 other plants in the garden that appear fine.

Thoughts on what it is would be greatly appreciated. Unfortunately, I'm out of town for the next week.