Honey Locust

(Gleditsia triacanthos var. inermis)

A popular Colorado shade tree valued for its filtered light, drought tolerance, and fast growth. While adaptable, Honey Locust is vulnerable to leaf-feeding insects, pod gall midge, canker diseases, and root/environmental stress in compacted urban soils.

Seasonal Pest & Disease Calendar

Problem Type Active Season
Honey Locust plant bug Insect Spring
Honey Locust pod gall midge Insect Late Spring–Summer
Leafhoppers / Locust leafminer Insect Summer
Spider mites Mite Summer (hot/dry)
Canker diseases (Nectria, Thyronectria) Fungus Spring–Fall
Root decline (compaction, drought, overwatering) Abiotic Summer–Fall

Pest & Disease Guide (Homeowner-Friendly)

Honey Locust Plant Bug

Common symptoms
  • Leaves stippled or distorted in spring
  • Premature leaf drop on new growth
  • Small green bugs visible when disturbed
Treatment & management
  • Usually cosmetic
  • Natural predators often control them
  • Professional spray only in severe outbreaks

Honey Locust Pod Gall Midge

Common symptoms
  • Leaves curl into pod-like galls
  • Tip dieback on new growth
  • Distorted, bumpy leaflets
Treatment & management
  • Prune off heavily infested tips
  • Avoid excessive nitrogen
  • Professional treatment if severe

Leafhoppers / Locust Leafminer

Common symptoms
  • Bleached, stippled leaves
  • Scorch-like browning in mid–late summer
  • Leaf skeletonizing in severe cases
Treatment & management
  • Typically cosmetic
  • Deep watering reduces stress
  • Professional treatment if widespread

Spider Mites

Common symptoms
  • Fine stippling or bronzing
  • Dusty, dull foliage
  • Mites visible via paper tap test
Treatment & management
  • Hose-rinse foliage
  • Deep irrigate during heat
  • Professional miticide if severe

Canker Diseases

Common symptoms
  • Sunken or swollen bark areas
  • Branch dieback from tips
  • Fungal tissue under bark
Treatment & management
  • Prune infected branches
  • Sanitize tools
  • No chemical cure

Root Decline / Environmental Stress

Common symptoms
  • Early leaf yellowing
  • Sparse canopy
  • Leaf scorch in midsummer
Treatment & management
  • Deep water every 2–3 weeks
  • Improve soil drainage
  • Avoid overwatering in clay soils

When to Worry vs. When It’s Cosmetic

When to Worry (action recommended)

  • Progressive branch dieback (possible canker)
  • Heavy canopy-wide gall formation
  • Unexplained mid-summer scorch
  • Rapid canopy thinning
  • Bark cracking or sunken trunk areas

These issues may require professional diagnosis and pruning.

Mostly Cosmetic (monitor only)

  • Light spring stippling from plant bugs
  • Localized leaf curling from mild gall midge
  • Minor bronzing from leafhoppers or mites
  • Early fall color from heat/drought
  • Occasional thin canopy spots

These typically resolve with proper watering and seasonal recovery.