Dig around the base of the tree and examine roots for vole damage. Try additional hand baiting with zinc phosphide-treated apples.
Place bait in as many vole runs and tunnels as possible.
The best times for baiting are in October and early November. Where voles are not numerous, thorough coverage of the orchard block may not be necessary. Treat adjacent fencerows or grassy areas along with the portions of the orchard in which trouble usually occurs. During heavy, persistent snow cover, a few voles can cause serious damage. Thus, it may be necessary to rebait in midwinter.