Powdery mildew of boxthorn

Arthrocladiella mougeotii is an obligate parasitic fungus recognized as the primary pathogen responsible for powdery mildew infections on plants belonging to the genus Lycium, commonly known as boxthorn or goji berry. This fungus belongs to the Erysiphaceae family and specializes in parasitizing the epidermal cells of the host plant.

The host range is primarily limited to Lycium barbarum and Lycium chinense. The infection manifests on various aerial parts of the plant, including leaves, stems, and occasionally fruits, leading to visible damage that can severely impact the quality and quantity of the plant's harvest.

Symptomatology is characterized by the appearance of a white, powdery fungal mycelium covering the surfaces of leaves and young shoots. As the infection progresses, the mycelium thickens, and small, dark, spherical structures called cleistothecia develop, which serve as the overwintering stage for the pathogen.

Environmental conditions such as high humidity, warm temperatures, and poor air circulation significantly promote the development and spread of the fungus. Conidia, the asexual spores, are efficiently disseminated by wind currents, allowing the pathogen to spread rapidly through commercial plantations or garden settings.

The impact of this disease is significant, resulting in premature leaf senescence, stunt growth of shoots, and reduced photosynthetic capacity. Effective control strategies involve maintaining proper plant spacing for air circulation, implementing sanitation by removing infected plant debris, and applying targeted fungicides, such as sulfur-based products or systemic fungicides like triazoles.