Silky Specialty 9/10 - Frost Brush
This brush will give you a pretty layer of frost on trees and grass. Use a little for an accent, or go nuts and change the whole look of an image.
Once again, Silky Presets brushes are made to be used at Feather: 45, Flow: 50, and Density: 60, so make sure your settings are correct for ideal results!
If you need help installing your brush, try this video: https://www.youtube.com/watch?v=3dNz13iuQ8w