Dealing with dog waste on my property's lawn

[Edita D.]

Hey guys,
I was wondering if I am doing everything I can at this time to LESSEN the problem of ANIMAL WASTE at our un-fenced property. (This issue will be eliminated next year once we put a fence)
-called property management and had them call 2 of our tenants with dogs and advised them to pick dog waste as soon as the pet defecates.
-fixing up the property little by little to build up "pride of tenant ownership": if the property is updated and taken care of, tenants will be more reluctant to destroy/harm it.

I was also thinking of installing a ANIMAL WASTE STATION with a sign, trash basket and plastic bags, however it's 300$, and we will not need it within a year. My fiance thinks it's one of the tenants that is not picking up the dog waste, since a few months back the tenant said she "tries to pick up her dog waste every 3 days". When our property mng. company called to have her pick it up once the dog goes, she said the dog waste was actually from the "neighbors that let their pets go on our lawn". It's a little hard for me to believe, but at this time there's nothing we can do.
Any other suggestions, guys?