I have 2 Copperleaf shrubs outside.Thay are covered in a downy, powdery mildew.What causes this & what can I use to remove this? |
Powdery mildew fungi spread quickest when the humidity is high and temperatures are between 50F and 90F. To discourage the disease, plant on sites with good air drainage, give the plants plenty of space, water during the morning only, and allow the soil to dry out between waterings. You can sometimes stop widespread disease development if you remove any affected leaves as soon as you see that they are infected. It's too late for that with your copperleaf shrubs now so you may have to resort to using a copper based or sulfur based fungicide. Pruning the plants may be necessary to both open them up to better air circulation and to remove the dead leaves and stems that result from the powdery mildew. Fungicides include: sulfur, neem oil (Rose Defense, Shield-All, Triact), triforine (Ortho Funginex), or potassium bicarbonate (Kaligreen, First Step) Chemicals are most effective when combined with cultural controls. Best wishes with your landscape! |