Does using locally harvested honey help in treating seasonal allergies?

No. Many people believe that local honey will help treat or cure allergies, but this has not been proven.
Not logical. Bees gather nectar and pollen from visually attractive flowers. Allergies are not caused by this pollen, because it is too heavy to become airborne. Respiratory allergies occur in response to pollens that are windborne. They come from ugly plants that have.
Anectdotical evidenc. No studies have demonstrated that honey help; however, we hear from some patients of their benefit, while others don't. In order to have a rationale, the honey has to contain the pollen that the patient is allergic to. It might not be safe if there is enough pollen that the patient might develop a severe allergic reaction.