too much parsnip and/or parsley flavor
More potatoes and another apple - dilute (assuming "too strong" is really too strong, and not a just an unfamiliar flavor you would not like even if it was reduced. Parsnips can be polarizing.) 

Or add garlic and/or ginger until they overpower the parsnip and parsley (assumes you like garlic and/or ginger...) I guess chili might be another similar approach, but I wouldn't do that as I don't like it. I might add black pepper, though.