Something like this? (only do it as layers, not directly to the map, so you can fix overspray and other oopses.)

Click image for larger version.  Name: lake-dun-650-2.png  Views: 80  Size: 256.2 KB  ID: 62551

If so, I did it in Gimp. Used the default bristles 01, brush, size 25, jitter on at 3.0. I overlayed with the green from the grass, a 63943f medium green, a light pass with the dark green you have already in the woods, and finished with a very light pass of b09433 light brown.