--- title: Powdery Mildew canonical: https://fernland.com.au/problem-solver/powdery-mildew/ dateModified: 2026-08-07 09:46:06 summary: "Powdery mildew is a common fungal disease causing white powdery fungal growth on leaves, stems and buds of a wide range of ornamentals, turf, vegetables and fruit crops." type: article keywords: [Powdery Mildew, Erysiphaceae] --- # Powdery Mildew > Powdery mildew is a common fungal disease causing white powdery fungal growth on leaves, stems and buds of a wide range of ornamentals, turf, vegetables and fruit crops. *Erysiphaceae* Powdery mildew is not a single organism but a group of closely related fungi in the family Erysiphaceae, with different genera and species affecting particular host plants. Examples include Erysiphe, Podosphaera, Sphaerotheca and Leveillula species, each generally host-specific or limited to a narrow range of related plants. Despite this diversity, all powdery mildews produce a similar visible symptom and are managed in broadly similar ways. On the plant, powdery mildew appears as a talc-like, white to greyish-white coating of fungal mycelium and spores on the surface of leaves, stems, buds and sometimes fruit. As the disease progresses, the coating can thicken and cover large areas of foliage, giving leaves a dusty or floury appearance. Tiny, pinhead-sized black fruiting bodies (cleistothecia) may form within the mildew colonies later in the season, visible as black specks scattered through the white growth. Unlike most fungal diseases, powdery mildews do not require free water on the leaf surface to infect; spores germinate and spread readily in humid conditions even when foliage is dry, and infection is favoured by moderate temperatures, still air, shade and dense or crowded plantings that restrict airflow. Powdery mildew occurs across most of Australia and can appear at any time of year when conditions are favourable, though it is most active in mild, humid weather in spring and autumn. It affects an extremely wide host range in nursery, turf, horticultural and landscape settings, including roses, azaleas, grapevines, cucurbits, strawberries, tomatoes, pome fruit, cereals, canola and many turf species. Management relies on cultural practices that reduce humidity and improve airflow around plants, such as adequate plant spacing, pruning to open up dense canopies, and avoiding excess nitrogen which promotes soft, susceptible growth. Selecting resistant or tolerant varieties where available is an effective long-term strategy. In turf and cropping situations, monitoring during favourable weather and applying registered fungicides at first sign of disease, in line with label directions, helps prevent establishment and spread. ## How to identify - **White powdery coating:** the most obvious sign is a white to grey, dusty or floury fungal growth on leaf surfaces (often starting on the upper side but can occur on both), stems, buds and occasionally fruit. - **Leaf distortion and discolouration:** affected leaves may become distorted, curled, yellowed or stunted, and heavily infected leaves can dry out, turn brown and drop prematurely. - **Reduced vigour and quality:** flowering, fruit set and fruit quality can be reduced in ornamentals and fruiting crops; turf can show patches of thinned, weakened grass with a greyish cast. - **Black fruiting bodies:** tiny black specks (cleistothecia) may be visible within older mildew colonies, particularly late in the season. - **Field check:** rub a finger across the white coating — powdery mildew smears off as a fine dust, unlike downy mildew which produces a felty, greyish growth mainly on the leaf underside opposite yellow blotches on the upper surface. - **Lookalikes:** distinguish from downy mildew (favours wet conditions, growth concentrated on leaf undersides, angular yellow lesions above) and from dust, spray residue or scale insect coverings, which do not spread or thicken over time the way powdery mildew colonies do. ## Registered products we stock - [Tombstone Duo Fungicide](https://fernland.com.au/tombstone-duo-fungicide/) — ProForce - [Stellar 250SC Fungicide](https://fernland.com.au/stellar-250sc-fungicide/) — PCT SureFire - [Tridim 250EC Systemic Fungicide](https://fernland.com.au/tridim-250ec-systemic-fungicide/) — Colin Campbell Chemicals - [Bumper 625EC Fungicide](https://fernland.com.au/bumper-625ec-fungicide/) — Adama - [Triforine Rose Fungicide](https://fernland.com.au/triforine-rose-fungicide/) — Kendon - [Azoxystrobin 250SC Fungicide](https://fernland.com.au/azoxystrobin-250sc-fungicide/) — EnviroMax - [EcoCarb | Fungicide](https://fernland.com.au/ecocarb-fungicide/) — Organic Crop Protectants - [Trifend Insecticide, Fungicide & Miticide Garden Spray](https://fernland.com.au/trifend-insecticide-fungicide-miticide-garden-spray/) — Searles - [Wettable Sulphur Fungicide & Miticide](https://fernland.com.au/wettable-sulphur-fungicide-miticide/) — Amgrow Specialty Agriculture - [EcoCarb PLUS | Fungicide](https://fernland.com.au/ecocarb-plus-fungicide/) — Organic Crop Protectants - [Lime Sulfur Insect & Disease Control](https://fernland.com.au/lime-sulfur-insect-disease-control/) — Yates - [Dedicate Turf & Ornamental Fungicide](https://fernland.com.au/dedicate-turf-ornamental-fungicide/) — Envu - [Searles Wettable Sulphur Fungicide & Miticide](https://fernland.com.au/searles-wettable-sulphur-fungicide-miticide/) — Searles ## Image credits - [Photo: Juan Carlos Fonseca Mata via Wikimedia Commons (CC BY-SA 4.0)](https://commons.wikimedia.org/wiki/File:Erysiphe_euonymicola_(mildi%C3%BA_polvoriento)_mx.jpg) - [Photo: B. Schoenmakers (Waarneming.nl) via Wikimedia Commons (CC BY 3.0)](https://commons.wikimedia.org/wiki/File:Erysiphaceae_indet._(Erysiphaceae),_Elst_(Gld),_the_Netherlands.jpg) - [Photo: https://www.inaturalist.org/photos/226555959 via Wikimedia Commons (CC BY 4.0)](https://commons.wikimedia.org/wiki/File:Cystotheca-quercina-curren.jpg) - [Photo: https://www.inaturalist.org/photos/226555987 via Wikimedia Commons (CC BY 4.0)](https://commons.wikimedia.org/wiki/File:Cystotheca-quercina-curren-underside.jpg)