A wind turbine blade includes an upper shell member and a lower shell member with an internal cavity therebetween. The shell members are joined at leading and trailing edges of the blade with a bond paste along a bond line having a designed width. A barrier is disposed within the internal cavity between the upper and lower shell members along at least one of the leading or trailing edges and prevents movement of the bond paste into the internal cavity beyond the width of the bond line. The barrier includes a wall that is substantially impermeable to the bond paste and a support member that extends from the wall to the leading or trailing edge of the blade. The support member locates the wall at the bond line and the wall has a shape and resiliency so as to be engaged against the upper and lower shell members within the internal cavity.