Leaf IssuesSerious
White Spots or Patches on Cannabis
White on cannabis leaves can mean powdery mildew (bad), trichomes (good), mite damage (bad), or calcium spots (bad). The pattern tells you which.
What it looks like
- ●Powdery mildew: white DUSTY or FUZZY patches that wipe off
- ●Trichomes: tiny sparkly crystal hairs (natural, only in flower)
- ●Mite damage: tiny white/yellow pinprick dots (stippling)
- ●Calcium spots: white-centered brown rust spots
Quick diagnostic checks
1Wipe a patch — if it smears/comes off, it's PM
2Use a loupe — moving dots = mites, sparkles = trichomes
Causes ranked by likelihood
1. Powdery mildew (most urgent)
Most commonSigns
- ●Dusty patches that wipe off
- ●Spreading fast
- ●High humidity
Fix
- ✓See full powdery mildew guide — act fast
2. Spider mite stippling
CommonSigns
- ●Pinprick-sized dots
- ●Tiny specks moving on undersides
- ●Fine webbing
Fix
- ✓See spider mite guide — neem spray, predatory mites
3. Trichomes (this is normal!)
CommonSigns
- ●Sparkly crystal-like hairs
- ●Only on flower-stage plants
- ●Concentrated on buds and sugar leaves
Fix
- ✓Nothing — trichomes = potency. This is what you want.
⚠️When to worry
PM or mites = urgent action today. Trichomes = relax.
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