Blake Wheeler wrote:A cheap option I'm using, though I don't deal with with cattle or hogs, has been black drainage pipe, the kind you attach to gutter downspouts and such. Roughly $6 for 15 feet. Cut it to length, cut a slit down the length of it and slip it around the tree. Also found it useful in small sections to keep mulch away from the bases and grafts of trees. About the only "livestock" problem I have is the neighbors cat and dog tossing mulch everywhere and burying the tree trunks in it. Fits lose enough to allow airflow and keeps rodents away from the bark.
I've found ADS-type corrugated drainage tile to be detrimental. Black color is too prone to solar gain and cooking trees, too opaque to encourage growth, and only functionally useful to discourage girdling after the tree is of sufficient height to be above the tube...meaning it was entirely exposed when young.
White drainage pipe, if available, is marginally better in my opinion.