Troubleshooting
Ostbo Red Mountain Laurel problems — and how to fix them
Ostbo Red Mountain Laurel (Kalmia latifolia 'Ostbo Red') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Leaf spot and blight
Phytophthora blight and various fungal leaf spots (Botryosphaeria, Mycosphaerella) cause brown lesions on leaves. Improve air circulation by thinning crowded stems, avoid overhead watering, and remove infected material. Fungicide may be needed in persistently wet seasons.
Lace bug (Stephanitis pyrioides)
Lace bugs feed on the undersides of leaves, causing stippled, bleached foliage and black tar-like excrement. More common on plants in full sun. Insecticidal soap or neem oil applied to leaf undersides in late spring controls nymphs effectively.
Chlorosis
Yellowing between leaf veins (interveinal chlorosis) indicates iron or manganese deficiency from soil pH above 6.0. Lower pH with elemental sulfur and apply chelated iron as a foliar spray or soil drench. Test soil pH before planting.
Prevent ostbo red mountain laurel problems before they start
Most ostbo red mountain laurel issues are care-mismatch, not bad luck. Dial in the basics:
Ostbo Red Mountain Laurel problems — FAQ
Why is my ostbo red mountain laurel leaf spot and blight?
Phytophthora blight and various fungal leaf spots (Botryosphaeria, Mycosphaerella) cause brown lesions on leaves. Improve air circulation by thinning crowded stems, avoid overhead watering, and remove infected material. Fungicide may be needed in persistently wet seasons.
Why is my ostbo red mountain laurel lace bug (stephanitis pyrioides)?
Lace bugs feed on the undersides of leaves, causing stippled, bleached foliage and black tar-like excrement. More common on plants in full sun. Insecticidal soap or neem oil applied to leaf undersides in late spring controls nymphs effectively.
Why is my ostbo red mountain laurel chlorosis?
Yellowing between leaf veins (interveinal chlorosis) indicates iron or manganese deficiency from soil pH above 6.0. Lower pH with elemental sulfur and apply chelated iron as a foliar spray or soil drench. Test soil pH before planting.