Answer: I'm not aware of a fungal disease called rust affecting magnolias so I wonder if what you are seeing are the rusty colored hairs on the leaves and some bruising damage on the petals of the flowers. The petals might be damaged by wind which could cause a rusty colored area to appear. Why not take a few of the affected leaves and one of the flowers to your local cooperative extension office for diagnosis? Helpful folks there can confirm or rule out disease problems. Best wishes with your magnolia!
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