Loos like artic does not handle transparency or as a missing feature or bug.
As a workaround
what you can try, since there are a lot of trees with complex foliage and alpha blending problems, you can make imposters. In-game dev, imposters are just multiple planes containing the the image of the tree. You can make 360 screenshots of the tree and place some planes. So that fps will increase and that also let you apply transparency.