Mulberry

(Morus spp. — White, Red, Hybrid & Fruitless Mulberries)

Mulberries are tough, drought-tolerant shade trees known for fast growth, dense canopies, and (on fruiting types) heavy berry production. In Colorado, they are generally durable but can experience bacterial blight, leaf spot, mildew, scale, webworms, bronzing from mites, and environmental stress.

Seasonal Pest & Disease Calendar

Problem Type Active Season
Bacterial blight (Pseudomonas) Bacteria Spring–Early Summer
Leaf spot Fungus Spring–Summer
Powdery mildew Fungus Summer–Fall
Scale insects Insect Spring crawlers; visible year-round
Spider mites Mite Summer–Fall
Fall webworm Insect Late Summer–Fall
Aphids Insect Spring–Fall
Environmental heat/drought stress Abiotic Summer–Fall

Pest & Disease Guide (Homeowner-Friendly)

Bacterial Blight

Common symptoms
  • Black, water-soaked leaf edges
  • Blighted new shoots
  • Leaf curl or early drop
Treatment & management
  • Prune affected shoots
  • Sanitize tools
  • Avoid overhead irrigation
  • No chemical cure (seasonal issue)

Leaf Spot

Common symptoms
  • Brown or black spots
  • Leaf drop
  • Usually cosmetic
Treatment & management
  • Rake leaves
  • Improve airflow
  • Rarely needs fungicide

Powdery Mildew

Common symptoms
  • White powdery coating
  • Distorted growth
Treatment & management
  • Increase sunlight
  • Improve airflow
  • Fungicide if severe

Scale Insects

Common symptoms
  • Hard bumps on twigs
  • Honeydew and sooty mold
  • Thinning canopy
Treatment & management
  • Dormant oil in winter
  • Treat crawler stage
  • Prune infested areas

Spider Mites

Common symptoms
  • Bronzing or stippled leaves
  • Dusty appearance
  • Fine webbing
Treatment & management
  • Rinse foliage
  • Increase humidity
  • Miticide if severe

Fall Webworm

Common symptoms
  • Webbed nests
  • Foliage eaten inside webs
Treatment & management
  • Remove nests early
  • Professional treatment if widespread

Aphids

Common symptoms
  • Honeydew
  • Sooty mold
  • Leaf curling
Treatment & management
  • Hose off foliage
  • Encourage predators
  • Treat if severe

Environmental Stress

Common symptoms
  • Leaf scorch
  • Early yellowing
  • Sparse canopy
Treatment & management
  • Deep water every 2–3 weeks
  • Mulch 2–3"
  • Avoid heat-reflective sites

When to Worry vs. When It’s Cosmetic

When to Worry (action recommended)

  • Severe leaf blight causing defoliation
  • Heavy scale with black mold buildup
  • Branch dieback
  • Severe mite bronzing
  • Large webworm infestations
  • Decline in drought or compacted soil

Chronic issues or stress may require professional evaluation.

Mostly Cosmetic (monitor only)

  • Light leaf spot or mildew
  • Small webworm nests
  • Minor mite damage
  • Early yellowing
  • Occasional aphids

Most issues are aesthetic and do not threaten overall tree health.