Impatiens Pest and Disease Management: IPM Strategies Including Downy Mildew

Impatiens Health Management

Impatiens face significant pest and disease challenges, none more devastating than impatiens downy mildew, which transformed the impatiens industry in the 2010s. Understanding disease prevention, pest management, and resistant variety selection is essential for successful impatiens growing.

Impatiens Downy Mildew: A Game-Changing Disease

Background

Susceptibility by Type

Symptoms Progression

Note: Symptoms can progress from healthy-looking to dead within a week under favorable conditions.

Favorable Conditions

Management Protocol

If You Find Infected Plants:

1. Do NOT wait—act immediately
2. Remove entire plant including roots
3. Remove plants within 3 feet (likely infected)
4. Bag plants before moving (prevents spore spread)
5. Dispose in trash—NEVER compost
6. Clean tools with 10% bleach

Prevention:

Fungicide Prevention (only for high-value situations):

Long-Term Site Management

Alternatives to Traditional Impatiens:

• Begonias (wax and tuberous)
• Coleus (foliage)
• Torenia (wishbone flower)
• Alternanthera (foliage)
• Caladiums (foliage)
• New Guinea impatiens
• SunPatiens

Other Fungal and Bacterial Diseases

Stem Rot/Root Rot

Management:

• Ensure excellent drainage
• Avoid overwatering
• Don't plant too deep
• Use fresh, clean potting mix

Botrytis (Gray Mold)

Management:

• Remove dead plant material
• Improve air circulation
• Avoid overhead watering
• Reduce humidity

Bacterial Leaf Spot

Management:

• Remove infected leaves
• Avoid overhead irrigation
• Improve air circulation

Viral Diseases

Impatiens Necrotic Spot Virus (INSV)

Tomato Spotted Wilt Virus (TSWV)

Virus Prevention:

• Control thrips populations
• Remove and destroy infected plants
• No cure exists—prevention only

Insect Pests

Spider Mites

Management:

Aphids

Management:

Thrips

Management:

Slugs and Snails

Management:

Whiteflies

Management:

• Yellow sticky traps
• Insecticidal soap
• Neem oil

Integrated Pest Management (IPM)

IPM Principles

Cultural Prevention

Monitoring Schedule

Biological Controls

Quick Diagnostic Guide

Resistant Variety Decision Guide

Prevention through resistant variety selection, good cultural practices, and early detection remains the foundation of impatiens health management.