Damage to a tree most likely from elk. (Photo: CSU Extension Boulder County).

In previous articles, I have written about the damage rodents and small mammals cause to your landscape plants, but larger mammals such as deer, elk and bobcats can damage landscape plants too.

Deer and moose are browsers meaning they predominately eat forbs (broadleaf plants) and shrubs and trees but also graze grasses. Elk are mainly grazers but browse forbs and shrubs when grass is lacking or unavailable. Fruit trees such as apples are a favorite browse. These mammals can also use your trees and shrubs to remove the velvet from their antlers prior to the rut.

Fencing around plants is the surest way is to exclude them from accessing plants both as food and to remove antler velvet. Use heavy duty woven or welded fence material to build a circular exclosure around the plant securing it to four t-posts or other stakes pounded into the ground. The enclosure should be larger than the farthest out branches allowing space for plant growth and if the animal decides to use the fence for velvet removal. A five-foot high fence is adequate for deer, but higher fence may be needed for elk and moose. An electric fence is also effective. To make the electric fencing effective, put peanut oil or peanut butter on the wire prior to electrifying it. When the animals lean against the fence, they do not feel the shock as their hide is thick enough to insulate them. They are attracted to the peanut smell and either stick their nose to the wire or lick it. This gives them just enough of a shock (not enough to harm them) that it deters them from feeding on the plant.

Other methods to deter them from browsing are bud caps, taste and smell repellents. Bud caps are simply pieces of paper stapled around the new buds on conifers. They are labor intensive to install, and deer can learn to remove them, or they may blow off in high winds. Repellents are effective, but you need to reapply them periodically and you need to change the repellent type (main ingredient) periodically, so they don’t get accustomed to the taste or smell. Two ingredients in taste repellents that have been proven to be effective are capsaicin (hot sauce) and putrescent egg solids. If you use the capsaicin (hot sauce) make sure that you use the 100X (6.26 percent) version, lower percentages are less or not effective at all.

Odor/smell repellents deter by the odor they emit. Putrescent egg solids emit sulfur compounds (rotten egg odor) which deters wildlife. The other smell deterrent is blood meal. We won’t notice these odors, but the wildlife can smell them. Big game repellents containing putrescent egg solids have proven to be effective. You can make your own egg solid repellent by mixing a dozen eggs with enough water to make a gallon. The mixture can be put in a sprayer for application. To keep the sprayer from clogging, remove the chalaza (the white membrane attached to the yolk) and strain the mixture before putting in the sprayer. Repellents must be reapplied periodically as precipitation and sunlight break them down. It’s also a good idea to change which main ingredient you use. That keeps the animals from getting accustomed to the repellent and just ignoring it.

Domestic cats and wildlife such as bobcats and porcupines cause damage to trees by scratching the bark. The only way to deter them is by wrapping the trunk with hardware cloth (three feet high for the cats) or metal flashing (three feet high for porcupines). The flashing or wire must be expanded as the trunk grows to not damage the tree.

By Sharon Bokan, Colorado State University Extension Boulder County. Sharon is the Small Acreage Coordinator at Colorado State University Extension Boulder County. For more information call 303.678.6176, e-mail [email protected] or visit ext.colostate.edu/boulder.