grass animation changing color

i've added a grass texture, and when i look at it through the camera, it changes color from yellow to green and back to yellow during about 5 seconds, i have set both healthy and dry color to yellow since it's supposed to be dry grass... what's up with that? anyone?

Just to answer this quickly, you can change the “Grass Tint” in the last tab of the Terrain properties.

Best explanation I found:

“…under the main terrain settings, set “Grass Tint” to a 50% gray value (r=g=b=128)”

Also found Forum post talking about this ‘feature’ from 2010
http://forum.unity3d.com/threads/need-terrain-grass-single-colour.53593/