Damage on the Bottom Row of Arborvitae

Arborvitaes are evergreen shrubs that are often used as screens, windbreaks or as specimen trees. These shrubs are also known as white cedar, American arborvitae or Eastern Arborvitae. Although arborvitaes are lovely, these shrubs often become damaged and discolored in the winter months, often from wildlife feeding, winter injury or salt damage.

Causes

Arborvitaes often sustain damage on the lower portion of trees from small animal feeding, such as rabbits. Plants such as roses, viburnum, sumacs, dogwoods, cotoneasters, arborvitaes and pines are a food source for rabbits. Arborvitaes usually sustain the majority of damage to the lower portion of the tree. Salt injury is common in arborvitaes, and most of the damage is evident on the bottom portion of trees on the side facing the roadway. Salt runoff can also damage evergreens and cause the tree to have difficulty with water uptake.

Effects

Rabbit feeding strips arborvitaes of bark around the bottom portion of the trunk, often girdling the entire tree. Stems and twigs may be completely severed from the shrub, and feeding injuries extend as far as the animal can reach. Salt damage from de-icing is common in the winter months on evergreens. Salts placed on roadways can splash onto arborvitaes growing close to the road, and damage is often only on one side of the tree. The bottom portion of arborvitae may be damaged by salt runoff, with the needles turning yellow, then brown. Evergreens suffering salt injury often die as a result.

Cultural Control

Rabbits generally come into home landscape settings to feed when their food sources are limited and the competition for food is great. The damage to the lower portion of evergreens is often irreversible, with many evergreens permanently losing their lower branches. Arborvitaes and junipers may produce new buds the following spring, but those with extensive damage may die from feeding injuries. Soil testing may help homeowners to determine whether the damage to their arborvitae is from salt injury. Trees and shrubs with severe damage may recover from salt spray, but it often takes several months before the tree appears healthy again.

Considerations

Evergreens are susceptible to a variety of environmental stresses. Providing your arborvitae with adequate amounts of water helps prevent drought stress and keeps your tree healthy. Mulching will help hold in moisture around the tree, warding off drought stress. Placing repellents on your evergreens may help reduce wildlife feeding. Contact repellents are placed on the bark and foliage of trees, causing them to taste bad. However, if rabbits and other wildlife are hungry, any tree may sustain damage from feeding. Control salt injuries by installing splash guards or spray guards near your arborvitae, especially on the side facing the roadway.

References

• Iowa State University Extension; Winter Damage to Trees and Shrubs; Richard Jauron; March 2001
• Ohio State University Extension; Evergreen Trees for Ohio; Jane C. Martin
• Ohio State University Extension; Yellowing, Dieback and Death of Narrow-Leafed Evergreens; Stephen Nameth, Nancy Taylor and Jim Chatfield