Answer: Pressure treated wood is fine to use for a trellis, but I wouldn't recommend using it in a vegetable garden. This is because the chemicals might leach into the soil and contaminate the underground veggies. Growing grapevines on a pressure treated trellis should not contaminate the grapes because they will not make direct contact with the lumber. Grapes hang down and away from the vines so they should be free and clear. If any grape bunches rest directly on the lumber you can prune them off rather than harvesting them. Hope this clarifies things for you.
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