[bcday]

What antifungal did the nursery suggest? Most of the anti-fungal foliar sprays that are safe for home gardeners to use on vegetables act by coating the foliage with a physical barrier that prevents the fungal spores from accessing the leaf. They were not designed for use as a soil drench and wouldn't kill any fungus in the soil. If your plants have one of the three foliar fungal diseases I mentioned above (Early Blight, Late Blight, or Septoria), soaking the roots with a foliar anti-fungal spray won't help. Those three diseases don't grow on or in the roots at all and don't live in the soil by themselves either.

The antifungal solutions that are used on commercial farm soils for the soil-borne Fusarium or Verticillium require special equipment, are not safe for home gardeners to use, and are generally not available to people who aren't licensed to use them. There are folks here on the forum who can advise you as to how they deal with Fusarium and Verticillium if your plants become infected with one of those.

If you want to buy something to soak the roots with, read the label instructions thoroughly first to see if the product is intended for that use.