This might temp you into LR5 upgrade . . .
As mentioned above, I used the defringe tool to remove most of the color. You'll notice that it doesn't get all of it.
I then applied a radial gradient with an "inverted mask" to that area of the image and lowered the contrast, highlights and most important the saturation. Then, I ran the defringe slider all the way to 100%. Since the inverted radial gradient works from the "middle out" it seemed to do a decent job in neutralizing the purple in the area affected. I then played with the size and shape and orientation of the radial, and the amount of feather. I then bumped the clarity a bit to return some midtone contrast lost by the overall contrast adjustment. My efforts were 'quick and dirty' and I'm sure you could get it better and more subtle with a little close attention to this approach. You could add a second, and smaller rg to the cluster of branches to the right that also still has residual purple.