I originally tried an image that was similar to this. Problem was what I wanted in grayscale already looked in grayscale. Left the image not looking desaturated, which is what I'm seeing here. I really like the idea, the texture is great. But it gives an illusion of not being selectively desaturated, only my opinion.
Ok, I see what you were going for. But it doesn't really feel like an image that has been selectively desaturated. Overall, the composition lacks some punch.
You might have emphasized the blue sky more if you had the tree in gray. With such a large percentage of the picture in color and with tombstones that are usually gray anyway, it's kinda hard to see the desaturation.
I believe you had a great idea behind this but the graves don't lend themselves to desaturation... the sky and tree don't really 'jump out at you' since the image doesn't look like anything was desaturated. Might have worked better had you also desaturated the tree or the sky and thereby emphasize one or the other.