here in missouri we don't have that problem, at least not that i am aware of. anyway, the pvc trees seem to do really well for me. i think the secret is to use the darkest pipe you can find and then take a really heavy grit sandpaper to it. scar the crap out of it so algae can grow on it easier and it will be covered in 2 weeks under the right conditions. if you sink a cedar within 5 feet of them they work even better! that is of course assuming that the state allows such mischevious activities. to the cpo that may be reading the board, check my profile and if you are who i think you might be, pm me. otherwise, be safe.
"We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect"
-Aldo Leopold