Best defense is deliberate diversity

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.