Bindweed powdery mildew

The causative agent of this disease is the parasitic fungus Erysiphe convolvuli, which is a member of the order Erysiphales. This pathogen is an obligate parasite, living on the surface of plant tissues and utilizing specialized structures called haustoria to extract nutrients from the host's epidermal cells, which significantly disrupts the plant's metabolism.

The primary host for this fungus is the field bindweed (Convolvulus arvensis). While it is a common weed, the pathogen specifically targets the foliage, petioles, and stems, creating a white, flour-like fungal growth that coats the infected plant parts as the fungus develops its mycelium and conidial spores.

Symptoms of the infection typically appear as small, white powdery spots on either side of the leaves. As the disease advances, these spots coalesce until the entire leaf surface is covered with a thick white mat. This often leads to chlorosis, leaf curling, and in severe cases, the premature senescence and death of the infected plant tissue.

• Warm and humid conditions (optimum temperature range +18°C to +26°C).
• Dense foliage providing favorable microclimatic conditions for fungal growth.
• High humidity or dew formation during the night and early morning hours.
• Wind-borne dissemination of asexual spores across agricultural fields.

The agricultural importance of this disease lies in the impact on plant vigor. By weakening the bindweed, the fungus may limit the competitive capacity of this aggressive weed. However, excessive spread of Erysiphe convolvuli within a field indicates an environment that may also support the development of related powdery mildew species that attack commercial crops.

Effective management focuses on limiting the inoculum source and promoting plant health. Cultural practices such as crop rotation, thorough weed management, and field sanitation play a critical role in preventing the build-up of the pathogen. If chemical control is required, systemic fungicides, particularly those containing triazoles or strobilurins, are effective at inhibiting the development of the fungal mycelium.