Preheat the oven to 375 degrees F (190 degrees C).
Press the pie crust into the bottom and up the sides of a 9 inch pie plate. In a large bowl, stir together the sugar and flour. Mix in the lemon zest and lemon juice. Gently stir in the blueberries. Pour into the pie crust.
In a medium bowl, stir together the brown sugar, oats, flour and cinnamon. Mix in butter using a fork until crumbly. Spread the crumb topping evenly over the pie filling.
Bake for 40 minutes in the preheated oven, or until browned on top. Cool over a wire rack.
Frost is a common problem with wild blueberries and is the primary cause of a poor harvest. Not all blueberry farms have the same climate. The fields in Quebec and Maine blossom before the fields on Prince Edward Island and are therefore more susceptible to frost. The later blossoming of Island berries usually occurs after the last frost of the spring.