Quick ID Guide
Root Damage & larvae
What You’ll See (Visual Identification)
Description:
Powdery mildew appears as a white or gray powdery coating on the surface of leaves, stems, or buds. It often starts as small circular spots and spreads into larger patches, eventually covering entire leaf surfaces. Unlike many other fungal diseases, it sits on top of the leaf, not inside it.
Quick checklist:
White, dusty, flour-like spots
Circular patches that expand outward
Found on upper leaf surfaces first
Leaves may yellow, curl, or dry out later
Damp Soil & Draining Trays
Description:
Powdery mildew prefers low airflow and shaded areas. It often starts on lower leaves, inner canopy, and dense growth zones where humidity lingers and air circulation is poor.
Quick checklist:
Lower and older leaves
Shaded interior canopy
Crowded plant areas
Stems and petioles
Where to Look First (Common Hotspots)
Why It Happens (Conditions That Trigger It)
Description:
Powdery mildew thrives in humid environments with poor airflow, but unlike other fungi, it does not require standing water. It spreads rapidly through spores carried by air, tools, or clothing.
Quick checklist:
High humidity (40–70%+)
Poor air circulation
Crowded plants
Warm days and cool nights
Powdery Mildew
Identify powdery mildew by its white powdery spots on plant leaves that look like flour or dust. Early signs of powdery mildew start as small white circular patches that quickly spread across leaf surfaces, stems, and buds. Unlike other fungal diseases, powdery mildew grows on top of the leaf surface, making it easy to see.
Fungus Gnat Larvae
Learn how to identify powdery mildew on plants with this quick ID guide. Discover early signs, white powdery mildew symptoms, causes, and where to check first to stop plant fungus fast.
Treatment Plan
Prune and remove leaves showing white powdery mildew spots. This reduces spores and slows spread. Dispose of debris outside the grow area and sanitize tools.
Remove Infected Leaves
Apply Green Cleaner IPM spray for powdery mildew to all leaf surfaces, including undersides. It kills mildew on contact and helps prevent regrowth. Repeat every 3–5 days if needed.
Spray Green Cleaner IPM
Reduce humidity to 40–50% and add fans to improve airflow. Powdery mildew thrives in stagnant, humid environments.
Lower Humidity & Increase Airflow
Use Green Cleaner IPM preventatively every 7–14 days and inspect plants often. Prevention stops future outbreaks early.
Prevent with Regular IPM Care
Prevention Checklist
To prevent fungus gnats in houseplants, let the top 1–2 inches of soil dry out between waterings, use pots with drainage holes, and empty saucers so roots don’t sit in standing water. Avoid frequent light watering that keeps the soil surface damp—this is where fungus gnat eggs are laid. For better fungus gnat control, water less often, improve airflow, and use a well-draining potting mix.
1
Avoid Overwatering
Improve Drainage
2
Opt for sterile, well-aerated soil mixes without excessive compost or organic matter, which can attract gnats. Adding perlite improves drainage and reduces moisture retention.
Remove Debris & Standing water
3
Promptly clean up fallen leaves, flowers, or other organic matter around your plants, as these provide food sources for gnat larvae and encourage infestations.
Allow the top layer of soil to dry out between waterings
4
Overwatering is a primary cause of fungus gnat infestations, as larvae need moist soil to survive. Let the top 1-2 inches of soil dry completely before watering again to discourage egg-laying.
Need a Product?
Root Cleaner
Fast and effective soil drench that helps eliminate fungus gnat larvae, flush out root-zone buildup, and support healthier plant roots for stronger growth in houseplants, raised beds, and container gardens.
Green Cleaner
Safe and effective integrated pest management (IPM) solution for natural & non-toxic pest control—helping you prevent and treat common garden pests like aphids, spider mites, whiteflies, and fungus gnats while protecting plants
Frequently Asked Questions
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Fungus gnats are commonly associated with overwatered houseplants, as they lay eggs in moist soil cracks and crevices. Infestations often worsen in fall when infested outdoor plants are brought inside, or from new plants, open bags of potting soil, or open windows.
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Adult fungus gnats do not feed on or damage plants but are a cosmetic nuisance. Larvae feed on decaying organic matter and fungi in soil, but in high numbers, they may damage roots by feeding on root hairs or tunneling into them, limiting nutrient uptake. Healthy plants with robust roots are usually unaffected.
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Females lay up to 200 eggs in clusters on moist soil, hatching in 3-6 days. Larvae develop through four stages over 1-2 weeks, then pupate near the soil surface. Adults emerge after 4-5 days and live about one week. The full cycle from egg to adult takes 3-4 weeks under optimal warm conditions,
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Fungus gnats will not go away on their own. You need to address the issue by reducing moisture, removing infested soil, or using traps and treatments, as small infestations can quickly grow due to their rapid breeding.
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Root Cleaner is an all-natural concentrate that kills fungus gnats and their larvae on contact, along with other soil pests and pathogens like pythium that cause root rot.
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Fungus gnats can be mistaken for fruit flies, but they have a Y-shaped vein pattern near the wing tips, while fruit flies do not. Fungus gnats are also typically found around houseplants and moist soil, whereas fruit flies are attracted to ripening fruit.