I have started approximately 200 trees at our farm in central Kansas. They are mostly hybrid oak trees and various fruit trees. All are in tree tubes. (We don't live at the farm, so I usually work on the trees to take a break from repairing fences, clearing land for the future pond, etc.)

I have lost several trees to various critters. I believe some of the damage is unintentional, and some is directed.

Any advice would be greatly appreciated! (On any of the topics.)

We have lots of dry periods too long for trees, so I have drip irrigation systems set up for most of the trees. We had a pretty bad drought last year and armadillos got a few trees. They are mostly insectivores. They burrowed around and under many of my trees. I believe my little wet "refuges" around each tree were the only places that insects were active during the drought. The armadillos were just following the insects.

I also have pocket gophers throughout the tallgrass prairie part of the farm. I think they mostly eat roots in my area. During the drought, my tree roots and the adjacent grasses and forbs (that caught some of my irrigation water) were the only things growing during the drought. The gophers killed several trees where they actually cut the roots, and killed others by having tunnels surrounding the tree and draining my water away from the roots.

I have weed fabric and mulch around some of the trees. I now have voles and mice burrowing under the fabric edges because it makes such a nice shelter. They have only girdled the base on one tree (during the winter), but I am worried they are going to do that more often as I increase their "shelters" around more trees.

The best solution I have researched so far is to spray diluted castor and surfactant on the ground around the trees. However, this only lasts a few weeks, and even less if there is a heavy rain. The theory is that the castor oil makes the roots unpalatable for the mice and gophers. Supposedly, it also makes the insects and grubs (that eat the roots) also unpalatable to the armadillos.

Can I spray the castor oil mixture directly on the basal trunk of the tree? (I would like my trees and roots to taste nasty.) Or is spraying oil on the base of small trees potentially damaging?

Any better ideas?

Thanks,
Fishin'Rod