Tree & Plant Diseases/Pests

tree decline
Diseases & Pests

What's Killing My Tree

Did you know that most tree problems result from a combination of factors? Insects and diseases often get the blame for killing trees, but factors like drought or construction damage are most likely the primary cause of a tree's death. These primary factors weaken a tree's defenses, making it more susceptible to attack by secondary invaders like insect borers and wood-decaying fungi.

+ see more - show less

Factors that can weaken trees include: 

+ see more - show less
  • mower or string trimmer damage
  • topping & other poor pruning practices
  • ice & wind storm damage
  • drought
  • flooding
  • late-season frost
  • severe winter weather
  • defoliation by insects or disease
+ see more - show less
  • improper planting
  • improper mulching
  • stem-girdling roots
  • acute pollution
  • increased pollution levels over time
  • herbicide damage
  • nutrient deficiencies
  • excessive salt accumulation
+ see more - show less
  • excessive fertilizer
  • soil compaction
  • changes in soil grade
  • changes in soil pH
  • construction damage
  • installing impervious surfaces
  • changes in water availability
  • changes in sunlight availability
+ see more - show less

Stressed trees are susceptible to a wide array of secondary stress factors, including Armillaria root rot, Hypoxylon canker, several defoliating diseases, and various insect borers and foliage feeders. It is often these secondary invaders that finally kill the tree.

+ see more - show less
Resources
EDD Maps

The Early Detection and Distribution Mapping System provides current information on invasive species and pests.

Missouri Invasive Forest Pest Plan

The Missouri Invasive Forest Pest Plan provides an overarching framework for a coordinated response in Missouri to invasive forest insects and diseases.

Urban Tree Decline

Tree decline is the gradual loss of tree health and vigor over time. Determining causes of decline requires careful examination of the tree and growing site as well as knowledge of the tree’s history.

Tree-Branch Flagging

Branch flagging, when brown leaves appear on individual branches scattered throughout the tree crown, can be caused by insects, diseases, or weather-related injury.