- Worldwide distribution. In Oceania, Australia, New Caledonia, New Zealand, Tonga. A disease of rose.
- Damage: white powdery growth (masses of spores) over surface of leaves, stems and flowers, causing distortions, leaf curling, and unsightliness of the flowers affecting appearance and economic value.
- Spread: spores in wind. Note, free water not needed for germination and infection. Survival unusual - fungal mycelium survives in the bud.
- Cultural control: in the nursery - check plants for infection; in the field/garden choose sunny, well-drained site, and space to allow good air circulation; water frequently, early morning, avoiding overhead irrigation; prune infected leaves, flowers; avoid over-fertilization; weed; resistant varieties.
- Chemical control: minerals (i) sulphur, copper, sodium (or potassium) bicarbonate; botanicals (ii) neem, garlic, rosemary, thyme, clove oils, vinegar; synthetics (iii) protectant fungicides - mancozeb or systemic fungicides - triazole or strobilurin. Milk can also be used.
Pacific Pests, Pathogens, Weeds & Pesticides
Rose powdery mildew (387)
Rose powdery mildew
Podosphaera pannosa; previously it was known as Sphaerotheca pannosa.
AUTHOR Grahame Jackson & Mani Mua
Information from Podosphaera pannosa. Wikipedia. (https://en.wikipedia.org/wiki/Podosphaera_pannosa); and Podosphaera pannosa (powdery mildew of rose) (2018) Crop Protection Compendium (www.cabi.org/cpc); and from Pegg K & Manners A (2015) Powdery mildew: A myriad of nursery pathogens. Agri-science Queensland, Department of Agriculture, Fisheries, Ecosciences Precinct, Brisbane QLD. https://www.horticulture.com.au/growers/help-your-business-grow/research-reports-publications-fact-sheets-and-more/powdery-mildew---a-myriad-of-nursery-pathogens/). Photo 1 Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org.
Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/18: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Pacific Community.