I have two hoya plants of this variety - one very old and one only about a year old. They both have red/brown dots on the underside of some of the leaves. On the older plant the brown spots show up intermittently on the plant, not just around the soil line. On the younger, most leaves are close to the soil and most leaves are affected. My guess from reading the previous posts is the problem is fungal. If so should i remove the affected leaves (probably not) and would Soap-Shield - a copper fungicide - or liquid sulfur be okay to treat them with?
They were both outside plants last summer in Minnesota. I never noticed the problem until returning home after 2 months of having a plant sitter care for them. Different watering regimen? Thank you for any suggestions.