One more question about vole guards- what about using grow tubes?
I contacted Mr. Tom Mills at https://www.treepro.com/ and asked him if they had any feedback regarding the use of tree tubes for the purpose of subterranean activity. Specifically, I noted in the FAQ’s they cautioned against burying the tubes (referenced below).
He mentioned that he had several growers that use their tubes in pine vole country without issue- their reason for cautioning against burying the tubes is the subsequent difficulty in removal.
He also said that many growers throw moth balls in the bottom of the tubes to dissuade mice from taking up residence- he mentioned that mice were more likely than voles to attempt habitation within the tubes themselves.
“ISN’T IT A FACT THAT MICE AND VOLES GET INSIDE THE TUBES, ESPECIALLY IN WINTER, AND THAT THEY OFTEN KILL THE TREE?
This is a bigger problem with our competitors’ products than is with ours. Tubes that aren’t vented, especially those that are pressed down into the ground, provide a cozy, comfortable place for critters to nest.
Our protectors and shelters can be vented or opened, which increases air circulation. During the winter, mice and voles really don’t find vented protectors offer much protection from the weather. In addition, we don’t recommend pressing the shelter into the ground. It should be snug to the ground but not stuck in the ground."