I have been doing applications for three years now with a Z-Spray and have never striped a lawn before, but I am starting to see some stripes show up on lawns that were done the last week of march, that had 50% slow release. they were all green, but the stripes are just starting to show up. I always thought my Z spread to the right, but never had any stripes because of it. I always spread back to my tire tracks. How long will these stripes last?