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Pink Knockout White Spots = Mildew (Not the Common Kind) + Basal Canes Are Normal

Pink Knockouts have white spots on older leaves only (not mildew, gardener says). Also large basal canes—gardener thought Knockouts don't get those. Has been pruning them.

White Spots = Mildew (Two Types Exist)

Powdery mildew (white powder) and downy mildew (white spots, often on older leaves). Both are fungal. Any rose fungicide clears it.

Basal Canes = Good!

Knockouts ARE roses—they throw vigorous basal breaks (new main canes from crown). Do NOT prune them off. They renew the plant. Pruning them weakens the bush.

Action

Spray fungicide for mildew.
Stop pruning basal canes.
Enjoy the renewal growth.

Roses: Transplanted Knockout Tree Rose Not Leafing Out in Alabama Heat; Overwintering Tree Roses in Cold Climates: Garage vs. Trench Method; Winter Protection for Pink Knock Out Tree Rose in Zone 4; Fire Blight on Knock Out Rose: Identification and Control; Holes in Knock Out Rose Leaves—Safer’s Spray for Chewing Insects; Planting Knockout Roses Closer Than Recommended: Pruning Makes It Work; New Knockout Roses: Purple Leaves and No Blooms – Transplant Sulk; Rosa 'Pink Knock Out' – Pink Shrub Rose; Pink Double Knock Out Rose: Bubblegum Pink Mutation, Black Spot Resistant; Pink Double Knock Out® Rose: Maintenance-Free Double Pink Blooms

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