Tenant doesn't pick up after pet

[Alejandro Diaz]

I own a duplex with one tenant living in each side. They share a front yard. One tenant has a basset hound and does not pick up after it. The non pet owner tenant has called, upset and complained about the poop situation. I sent her a message asking her 'to please make sure that yard was poop free since my landscaper would do a better job'. How can I resolve this in a nice way? Thanks.