Etho is a selective herbicide that can be used on Tall Fescue and Perennial Rye lawns as both a pre and post-emergent. This means it can be applied to your lawn at 40ml per 100m2 in 4-5 litres of water and left to dry on the lawn for post-emergent benefits, or follow the application with 3-5mm of irrigation for pre-emergent properties.
Keep pets and children off any treated areas until dry or ideally 24 hours.