Understanding Honeylocust Health

Written By Zac Giammarrusco

Honeylocust trees are iconic landscape fixtures—valued for their adaptability, elegant foliage, and resilient growth. But even sturdy trees like these face threats from diseases and pests. Colorado State University emphasizes that the top health hazards for honeylocusts are cankers and root collar rot, which can girdle and ultimately kill these trees ask.extension.org+14extension.colostate.edu+14fieldingtreecare.com+14.

1. Cankers: The Silent Killer

  • Causes: Fungi such as Thyronectria austroamericana, Nectria nigrescens, and Nectria cinnabarina lead to elongated, sunken, discolored bark lesions (see references)

  • Symptoms:

    • Bark becomes dead, sunken, or with thick ridges; dieback and premature leaf drop may follow - (see references).

    • Thin-barked areas may turn red-yellow, with loose bark and wine-red to yellow inner wood - (see references).

  • Prevention & Management:

    • Avoid wounding—prune cleanly, protect trunks from lawn equipment.

    • Promote vigor via proper watering, mulching, and seasonal pruning - (see references).



2. Root Collar Rot: Undermining From the Base

  • Cause: Soil microorganisms attack at the tree's base, causing bark/wood decay and girdling - (see references).

  • Signs:

    • Yellowing leaves in fall, gum oozing from the trunk near the ground.

    • Darkened wood, loose bark at collar level .

  • Care Tips:

    • Water the drip line, especially in dry seasons and winter.

    • Remove dead limbs and maintain soil drainage .

3. Insect & Mite Pests: Secondary Stressors

  • Common Offenders:

    • Podgall midge: Causes curled leaf galls in late spring; typically aesthetic but can stress young trees.

    • Plant bugs: Feed on new growth—manage only if growth damage is severe.

    • Spider mites: Especially in dry conditions, can infest leaves - (see references).

  • Treatment:

    • Monitor for mites; use water sprays or soaps.

    • Apply insecticides if plant bugs threaten growth; manage galls if they recur heavily - (see references).

4. Environmental Stress: Gateway to Disease

Colorado’s climate extremes—such as drought, late freezes, and tree damage—stress honeylocusts, making them prone to disease and pests - (see references).

  • Seasonal Care Strategies:

    • Maintain consistent watering schedules—supplement in dry fall and winter - (see references).

    • Mulch to stabilize soil temperature and moisture.

5. Wild Man’s Recommended Care Plan

✅ Prevention

  • Prune seasonally to remove dead or weak branches.

  • Avoid wounding the bark; train staff on careful equipment use.

✅ Vigilant Monitoring

  • Regularly inspect for cankers near wounds, collar-line rot signs, and pest infestations (galls, mites, bugs).

✅ Proactive Watering

  • Water deeply during prolonged dry spells, through winter, and at the drip line.

✅ Targeted Treatments

  • Fungal issues: No fungicides cure cankers—vigor and pruning are key.

  • Pests: Spot-treat when necessary; consider soaps for mites and insecticides for bugs/midge.

✅ Certified Arborist Support

  • For advanced issues (e.g., soil disease, large cankers), engage ISA-certified arborists to diagnose and treat.

Why Wild Man’s Tree Services?

  • We follow CSU best practices for honeylocust care - (see references).

  • Our trained crew avoids bark damage during maintenance.

  • We tailor watering and mulch plans to Colorado's unique conditions.

  • Seasonal inspections and treatments keep your trees healthy all year.

In Summary

Honeylocusts are resilient but require proactive care to avoid cankers, collar rot, pests, and environmental stress. Wild Man’s Tree Services uses research-based techniques to preserve these valued trees, helping them thrive in Colorado’s challenging climate. Reach out today to schedule an inspection or treatment plan! Let’s protect Colorado’s trees together.

🔗 References

Zac Giammarrusco
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