A very common fungal disease affecting a wide variety of plants. White, powdery deposit covering the surface of leaves and young shoots. Often smells a bit musty. Common on roses, apples and other fruit trees, courgettes, cucumbers and perennials such as lupins and delphiniums and some euonymous. More prevalent during hot dry summers.
Product solution: Consider using Systhane Fungus Fighter, Fungus Fighter Disease Control, Multirose 2 Ready-to-Use, Multirose Concentrate 2 where appropriate.
Cultural measures: Ensure that plants are kept well watered in dry spells and are not overfed. Remove infected plant debris and leaves.