What would be the economic rationale for homeowners associations to host "yard of the month" awards?

What will be an ideal response?

Homeowners associations clearly view beautiful yards as something desirable for the neighborhood. They not only provide direct benefits to those who keep up their yards but also bestow benefits on the rest of the residents as well. However, individual homeowners are not likely to take into account the positive externality they provide. As a consequence they are likely not to keep their yards as beautiful. The "yard of the month" award is an effort to get them to recognize those benefits. To the extent that those who participate make their yards more attractive, this helps to bring the beautification of the neighborhood to a more efficient level.