They move from plant to plant,,,are they Carriers ??
If sooo,,,,we're DOOMED...
No, slugs are not a vector for foliar nematodes. Foliar nematodes move from plant to plant mostly through rainfall and overhead watering. However, I have seen research that recommended washing tools after working on one plant before going to another. But people should be doing that anyway.
One of the ways of managing or limiting foliar nems is to remove the foliage of those plants with evidence of nems in the fall and disposing of it in the trash. Another is to not use overhead watering. This is one reason why drip irrigation is a preferred method of watering. A third is to simply remove any foliage that shows damage during the growing season and trashing that.
If you're in zone 4/5 you aren't going to see any damage until very late in the season. In your zone most people would choose to limit the damage as I have described. If you are in warmer zones and nems show up in late June or July, then it's a different matter.
well,,,THAT,,,at least,,,,is a RELIEF...,,