Hey, I’ve been exporting my blender foliage to UE4 and encountered this little issue at one of my fir trees.
I had the same problem in Blender at the beginning but tweaking the intensity helped.
PS: I made the alpha myself with GIMP, any way that i did not cut it out properly? It looks fine in GIMP
Hi -
Take a look at this tutorial made by Epic’s own Bill Kladis regarding the correct method for making Alpha Maps, Unreal Cascade: Making Proper Alpha Channels for VFX - YouTube
Thank You
Eric Ketchum
Well, the thing is I do not own UDK, nor PS 
Everything in that Video can be done in GIMP and applies to all game engines using an alpha map. You will just have to make adjustments based on how GIMP operates. The key point to take away is that you will need to generate a unmatted alpha.
Eric Ketchum
