We all love living in the rural west where encounters with wildlife are frequent and, usually, a bonus. But these same animals can cause significant damage to our precious landscapes. This is the third and final column on vertebrate damage to woody plants. This time we will cover large mammals including domestic animals such as horses.
Mule deer are the primary source of woody plant damage in Delta County. Their damage is both from browsing and antler rubbing. The antler rubbing from bucks occurs mostly during rutting in late summer and fall. This injury is the result of bucks trying to remove the velvet from their new antlers. Branch breaking and bark shredding often result.
Browsing damage to branches from deer results in ragged wounds from tearing. Damage from elk is similar. Rabbits, on the other hand, have teeth that allow clean cuts. This feeding occurs often at dawn or dusk when we least notice it. Elk also will “bark” aspen trees up to 6 feet in height. Many, many woody plants are browsed upon in our area including Austrian pine, Colorado spruce, lilac, forsythia, mugo pine, potentilla, sand cherry and three-leaf sumac. All of these plants have sustained damage in my yard or neighborhood unless caged. Many more plants are susceptible.
How do you prevent this damage from happening? Fencing is the surest way unless you consider not planting any deer-vulnerable plant species. There aren’t many of these. Single fencing needs to be about eight feet tall. Shorter closely spaced double fencing works because deer can’t high jump and broad jump at the same time.
Repellents do not have a good consistent track record for preventing deer or elk damage. Contact or taste repellants include hot pepper sauce which only protects treated plant parts, not the new growth that appears following application. Area or odor repellants include human hair, blood meal, and deodorant soaps. These are not very effective where deer are plentiful.
Commercial products including Deer-Away and Liquid Fence have worked for some but have failed miserably for me. I watched a doe feed on dripping wet Liquid Fence-treated sand cherry five minutes after application. Whether or not a repellent works may be more dependent upon deer density, how hungry they are, how many choices they have and if that sprayed plant is like desert to them. I find fencing to be the only guaranteed method for stopping deer damage. Or maybe get a dog.
Large domestic animals can cause lots of damage to trees. Horses, mules, donkeys, bison, cows, sheep, goats and pigs are all implicated here. Most damage occurs where these animals are confined in smaller fenced areas. They will chew the bark right off of large trees which can result in tree death. Chicken wire will prevent this.
Soil compaction around the base of trees will also adversely affect trees. And as the density of animals confined to a corral increases, the accumulation of their toxic waste can become a factor. The remedy for these two problems is simple. Remove animal waste to avoid excessive toxicity and put a large cage around the tree to prevent animals from compacting the soil in the root zone area.
While not a large mammal, cats can be a nuisance where they scratch trees. Any damage to the integrity of the tree’s bark from any of the animals discussed today can open the tree to disease such as cytospora canker, a prevalent disease which has no cure.
So there you have it. Prevention is the ticket to minimize any damage. The price you pay for living in western Colorado is balanced by the need to either select plants that are not damaged by birds and mammals, cage susceptible plants, or learn to accept a less than perfect garden.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.