Powdery mildew of Asteraceae

Golovinomyces cichoracearum is an obligate pathogenic fungus that serves as the primary causative agent of powdery mildew disease in many dicotyledonous plants, particularly those belonging to the Asteraceae and Cucurbitaceae families. As a biotrophic parasite, it derives its nutrients directly from the living cells of the host, weakening the plant's physiological functions.

The host range is extensive, including significant crops such as cucumbers, squashes, sunflowers, and various ornamental species. This pathogen is globally distributed and poses a serious threat to both open-field agricultural production and greenhouse operations, where it can rapidly overwhelm susceptible crop varieties if environmental controls are ignored.

The diagnostic symptoms involve the development of a white, mycelial, powdery film on leaves, petioles, and stems. As the infection advances, the leaves lose their dark green appearance, begin to chlorose, curl, and eventually necrotize. The presence of tiny dark spots, representing the fungus's fruiting bodies, may appear within the white mat during the later stages of development.

Development is most aggressive in warm and moderately humid conditions, yet unlike many other plant-pathogenic fungi, Golovinomyces cichoracearum does not strictly require free water on the leaf surface for spore germination. This characteristic makes it highly resilient and capable of spreading via wind-blown conidia throughout the entire growing season.

Economic damage is severe, resulting in stunted plant growth, reduced fruit set, and complete loss of marketability of the produce. Successful management strategies combine preventative practices and chemical interventions:

• rotation of crops to break the disease cycle;
• sanitation of crop debris and weeds;
• maintaining adequate plant spacing to increase airflow;
• timely application of sulfur-based or systemic systemic fungicides.