Opengl Trees blending problem

Hello,

I'm a new guy on this forum.


I have a small problem on trees blending see screenshot below.
I have two tests
- Alpha Test
- Alpha blending

    glEnable (GL_ALPHA_TEST);
    glAlphaFunc (GL_GREATER,.1f);

    glEnable (GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);


Is there a known principe in a shader to avoid this problem  ?

Do you know if i must use DEPHTBUFFER to make depth test ?

Thanks as advance.