Trees are valuable additions to the home landscape. When problems arise with the health of a tree, it can be difficult to determine what is causing the issue. Many factors can cause trees to become unhealthy and lose their aesthetic value or die. Some of those factors include:
- environmental stresses
- site problems
- animal injury
- infectious diseases
- insect infestations
Frequently more than one factor is involved. A correct diagnosis of the problem(s) is the important first step in trying to manage an unhealthy tree.
Often insects or diseases are the first things we look to when trying to pinpoint why a tree is unhealthy. However, in many cases, environmental stress and issues with the site (abiotic issues) are the primary cause of the problem, even when insects or disease-causing agents (biotic issues) are present. Those biotic issues are more likely to become an issue because the tree is weakened by abiotic issues.
Identifying Tree Problems
A thorough evaluation of the site, the growing conditions, and the tree itself is the first step to identifying the cause of the decline.
Identifying Tree Problems is a comprehensive resource that outlines the steps used for examining unhealthy trees.
Understanding Decline in Trees is a resource that provides tips on identifying, preventing, and reducing the factors that lead to tree decline.
It outlines several potential causes of decline in trees, particularly those problems related to the planting site and environmental conditions.
Help for Newly Planted Trees
Trees planted within the last three years are more likely to see problems than established trees.
Learn about the many factors that could contribute to the decline or death of a newly planted tree in this article: Decline of Newly Planted Trees
Resources for Common Tree Problems
Environmental Stresses
- Browning of Conifer Needles
- Winter Damage to Trees – including sunscald, desiccation, and rodent damage
- Frost and Freeze Damage
- Peeling and Splitting Bark
- Seasonal Needle Drop
- Understanding the Effects of Flooding on Trees (SUL 1)
- Managing Storm-Damaged Trees (SUL 6)
- Common Problems of Ash Trees (SUL 21)
- Construction Damage to Trees
- Grade Change Damage to Trees
- Nutrient Deficiencies in Trees
Insect Problems on Trees
- Scale Insects on Ornamental Landscape Plants (ENT 0040)
- Insect Galls on Trees and Shrubs (ENT 0039)
- Common Problems of Ash Trees (SUL 21)
- European Pine Sawfly
- Bagworm
- Carpenter Ants
- Cottony Maple Scale
- Emerald Ash Borer
- Magnolia Scale
Disease Problems on Trees
- Anthracnose of Shade Trees (PM 1280)
- Verticillium Wilt of Woody Plants (SUL 16)
- Cedar-Apple Rust
- Common Problems of Ash Trees (SUL 21)
- Fungal Cankers of Trees (SUL 11)
- Common Diseases of Conifers in Iowa (PM 1528)
- Oak Wilt - Identification and Management (SUL 15)
- Pine Wilt (SUL 9)
- Black Knot
- Dutch Elm Disease
- Oak Tatters
Common Issues with Conifers
- Conifer Disease Key
- Common Diseases of Conifers in Iowa (PM 1528)
- Pine Wilt (SUL 9)
- Browning of Conifer Needles
- Seasonal Needle Drop
- Rhizosphaera needle cast
- Stigmina Needle Cast
- Dothistroma Needle Blight
- Cytospora canker
- European Pine Sawfly
More information about the insect pests and diseases that can impact trees can also be found in the Encyclopedia. Those resources describe the insect or pathogen and management options.
