Fungal Severity: High ⚠️ Contagious

Cercospora Leaf Spot: Urgent! How to Save Your Plant

Cercospora leaf spot is a common fungal disease caused by Cercospora species that affects many plant types, particularly beets, roses, and leafy vegetables. The disease thrives in warm, humid conditions and can cause significant defoliation, reducing plant vigor and yield. It spreads rapidly through water splash, wind, and contaminated tools.

Spread speed

Fast

Recovery time

21 days

🔍 Symptoms

Main Symptoms

! Small circular spots (0.02-0.2 inch) on leaves
! Tan to gray centers with brownish-red to purple borders
! Spots coalesce into larger necrotic lesions
! Premature leaf yellowing and browning
! Progressive defoliation from lower to upper leaves
! Reduced plant vigor and yield

Visual Signs

Small circular spots 0.02-0.2 inch in sizeTan to gray centers with brownish-red purple bordersNecrotic lesions with purple-red marginsSpots group together into larger lesionsLeaves turn brown and collapsePremature defoliation

Affected parts: LEAVES

❓ Possible Causes

→ Cercospora fungi (multiple species)
→ Warm temperatures (75-85°F / 24-29°C)
→ High humidity (above 80%)
→ Prolonged leaf wetness
→ Overhead watering
→ Poor air circulation
→ Infected plant debris
→ Contaminated tools

💊 Treatment

⚡

Quick Fixes

~11 days

Step 1

Prune and destroy all infected foliage immediately

Step 2

Apply fast-acting systemic fungicide (propiconazole or Miravis Prime)

Step 3

Spray at first sign of disease (1-5 spots per leaf)

Step 4

Ensure complete coverage of all leaf surfaces

Step 5

Stop overhead watering immediately

Step 6

Reapply fungicide after 10-14 days

Step 7

Remove any new infected leaves weekly

Materials needed:

MancozebChlorothalonilAzoxystrobinPropiconazoleSprayerProtective glovesPruning shears

🌿

Organic Treatment

~21 days

Step 1

Remove all infected leaves and dispose in sealed bag (do not compost)

Step 2

Mix tank spray: copper octanoate (Cueva) + Bacillus amyloliquefaciens (Double Nickel LC) according to label rates

Step 3

Apply spray thoroughly to all leaf surfaces in early morning

Step 4

Improve air circulation by thinning dense foliage and spacing plants

Step 5

Switch to drip irrigation or water at soil level only

Step 6

Reapply organic fungicide spray every 7-10 days

Step 7

Apply compost tea weekly to boost plant immunity

Step 8

Continue monitoring for 4 weeks after symptoms disappear

Materials needed:

Bordeaux mixtureBaking sodaNeem oilBacillus subtilisDiluted milkSterilized pruning shearsMulchSpray bottle

🔬

Expert Treatment

~32 days

Step 1

Implement IPM monitoring: inspect plants every 3-5 days for early detection

Step 2

Begin preventative protectant fungicide (mancozeb or chlorothalonil) before disease appears

Step 3

When 1% of foliage affected (action threshold), switch to systemic fungicide

Step 4

Rotate fungicide modes of action: Group M (protectants) → Group 3 (DMI) → Group 7 (SDHI)

Step 5

Use tank mixes for enhanced control and resistance management

Step 6

Remove infected leaves during dry weather to prevent spore spread

Step 7

Deep tillage (6-8 inches) at season end to bury debris

Step 8

Rotate to non-host crops for minimum 3 years

Step 9

Use resistant varieties if available for your crop

Step 10

Monitor for fungicide resistance by tracking efficacy

Step 11

Apply fungicides preventatively during high-risk periods (warm + humid)

Step 12

Continue protectant sprays every 10-14 days until harvest

Step by Step

1
Remove all visibly infected leaves and dispose properly
2
Apply selected fungicide treatment when 1-5 spots per leaf are visible
3
For organic: mix copper octanoate + Bacillus spray
4
Spray thoroughly, covering all leaf surfaces
5
Reapply every 7-14 days depending on weather conditions
6
Continue treatment for 3-4 weeks after symptoms subside
7
Improve growing conditions: spacing, watering practices
8
Monitor weekly for new infections

🧪 Solutions

🌱 Natural Solutions

✓ Copper octanoate (Cueva) fungicide
✓ Bacillus amyloliquefaciens (Double Nickel LC)
✓ Tank mix of copper + Bacillus for enhanced control
✓ Neem oil as preventative spray
✓ Remove infected foliage and dispose away from garden
✓ Improve air circulation around plants
✓ Apply compost tea to boost plant immunity

💉 Chemical Solutions

✓ Chlorothalonil fungicide
✓ Mancozeb protectant fungicide
✓ Propiconazole systemic fungicide
✓ Pydiflumetofen + fludioxonil (Miravis Prime)
✓ Fluopyram + pyrimethanil (Luna Tranquility)
✓ Copper-based fungicides
✓ Rotate fungicides to prevent resistance

🛡️ Prevention

✓ Remove and destroy infected leaves immediately
✓ Ensure proper plant spacing for air circulation
✓ Avoid overhead watering; water at soil level
✓ Water in early morning to allow foliage to dry
✓ Practice crop rotation (3+ years for susceptible crops)
✓ Use deep tillage to bury infected plant debris
✓ Disinfect tools between plants
✓ Choose resistant varieties when available
✓ Apply preventative fungicides before symptoms appear

🌿 Common in These Plants

Flamingo Flower

Rose Painted Calathea

African Milk Tree

Heartleaf Philodendron

Moon Orchid