Sedum leaf spot

The causal agent of this disease is the fungus Boeremia telephii (syn. Ascochyta sedi). It is a specialized pathogen that primarily targets plants within the Crassulaceae family, leading to necrotic spots on leaves and stems, which can significantly affect plant vitality.

The disease is most commonly found on various species of Sedum (stonecrops), particularly Hylotelephium spectabile. While it rarely kills established plants outright, the infection severely reduces their aesthetic value and can weaken the overall health of succulent plantings in damp environments.

Symptoms typically manifest as small, dark brown or greyish spots on the leaves. As the infection progresses, these lesions enlarge and often develop characteristic tiny black fruiting bodies known as pycnidia in their centers. Severe infestations may lead to premature leaf drop and partial wilting of the stem tissue.

The development and spread of Boeremia telephii are heavily dependent on moisture and moderate temperatures. The spores are primarily dispersed by splashing water during rainfall or overhead irrigation. The fungus overwinters in crop debris, serving as a primary source of inoculum for the following growing season.

Effective management strategies should focus on both environmental control and sanitation:

• Remove and destroy all infected plant material promptly to limit spore production.
• Improve air circulation by providing adequate spacing between plants.
• Avoid overhead watering to keep leaf surfaces dry.
• Apply fungicides, such as those containing copper or systemic active ingredients, if the disease persists.