Best defense is deliberate diversity
Too much of a good thing is usually bad and it's no different with trees. The outbreak of Emerald Ash Borer in Boulder in 2013 and detection last summer in nearby Longmont makes the point. Already, this strange pest has killed billions of dollars of trees in 25 states and Colorado is now on the hit list. What's the lesson? What we think at any given moment is a solid choice of a tree to plant may be jeopardized in the future by a pest or disease we couldn't imagine at the time we dug the hole and planted our new tree.
When designing a new landscape, or adding to an existing one, variety is a good rule of thumb. The recommendation from Keith Wood of the Colorado State Forest Service is that, "No one species should comprise more than 10% of the planted trees." Planting too many of the same type of tree together is a set-up for future problems with insects and disease, he warns.
If you are planting new trees this growing season, keep these tips in mind:
- If you don't know the types of trees already on your property, get the help of a green industry pro to identify what you have.
- Find out if you have any ash trees in your yard - so you will have an action plan if/when the borer heads your way.
- Seek professional advice about what's best to plant in your yard and varieties that will work well with the plants and trees you already have.
- Follow care recommendations for water and nutrients to keep all plants healthy. Well-maintained plants that are consistently healthy and un-stressed are less susceptible to pests and diseases.
