The leaves from nut-bearing trees do not contain relevant tree nut allergens. The food allergen is found in the actual nut. Typically, the nut protein would have to be eaten for an allergic reaction to occur. Touching these leaves would not cause an allergic reaction.
Wheat protein would also have to be eaten to trigger an allergic reaction in an individual allergic to wheat. It is possible that direct contact with wheat grain could cause local skin reactions. This includes redness, skin irritation; less likely hives at the contact site. However, it would not cause a typical food allergy reaction. This is seen after eating the food.