[gregbradley]

Gradient channel technique.

Open image in PS
click on channels
click on add new channel
call it gradient
click on the gradient tool select the type of gradient which shows white triangle in one corner the rest black
drag a line about 1/4 the way from the right side where the gradient is.
It will create a white patch that fades out to the distance you dragged.
now click on rgb in channels
click on load selection and select gradient
now the area you made as a white patch shows up as a dotted line about 1/4 to the left of the right hand side of the image. Now any tool adjusts only that area.
Use levels and reduce the brightness of the gradient affected area. In your case that is mostly in the green channel so do it generally but also select green in levels and reduce that. That really got rid of it.
Unselect when done and you are finished.

Really you could achieve the same result more simply by simply lassooing the affected area then blurring the edge under refine edge so its a gentle reduction in lightness as it goes to the left. Then do the above.

I don't know if that dark patch to the right of the image is natural or an artefact. It was in the data before I did anything. Perhaps some artifact from previous gradient handlings. It does not look like its a natural part of the image.

Greg.