White spots = powdery mildew. Treat with baking soda spray: 1 tbsp per quart water, daily until cleared.
Beetles (likely Japanese or rose chafers): Hand-pick early morning or use rose insecticide.
Only the original red 'Knock Out' has proven disease resistance. Other colors (pink, white, etc.) are different varieties with varying resistance.
New plants often show stress symptoms – they'll settle in with consistent care.
White Spots on Photinia (Red Tip) Hedge: Insect or Fungal?
Sunset Maple Leaf Spot: Cosmetic Fungus, No Treatment Needed
New Knockout Rose Leaves Curling: Mildew or Fertilizer Burn?
Yellow Leaves on Double Knock Out Roses in Extreme Heat
Curling Leaves on Knock Out Roses: Multiple Possible Causes
Knockout Roses Losing Leaves in Atlanta: Drought Recovery Plan
Why Knockout Roses Drop Leaves in Summer Heat: Causes and Solutions
Zucchini Powdery Mildew: Identification and Milk Spray Treatment
White Spots on Dendrobium Leaves: Boisduval Scale or Mealybugs
Planting Knockout Roses in Clay Soil: Amend Heavily
Double Knock Outs Yellowing After Mushroom Manure: Winter Damage?
Yellow Spots on Knockout Rose Leaves: Weather Stress, Not Disease
Reviving Spindly Knock Out Roses in Houston: Heat, Alkalinity, and Pruning
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