Rotbrenner

Rotbrenner, caused by the fungus Pseudopezicula tracheiphila, is a destructive vascular disease affecting grapevines. In viticulture, it is frequently referred to as the «red burn» of vines, as the pathogen colonizes the xylem vessels, obstructing water and nutrient transport and causing localized tissue death in leaves.

The primary host for this pathogen is the domesticated grapevine (Vitis vinifera). The disease specifically targets the foliage, though in severe cases, it may compromise the rachis of the inflorescences. If left uncontrolled, the infection significantly impairs the plant's metabolic capacity, leading to poor wood maturation and weakened vines.

Early symptoms include the appearance of distinct lesions on the leaves, which are clearly demarcated by the venation. In white grape varieties, these spots appear yellowish or light brown, while in red grape varieties, they develop a striking red or dark crimson color. As the tissue dies, the affected leaf areas dry out, often leading to premature leaf drop.

The development of the disease is highly dependent on environmental factors, specifically cool and wet weather conditions during the spring. The pathogen overwinters as apothecia in fallen infected leaves. During rainy weather, ascospores are released and dispersed by rain splashes or wind, causing primary infections on the lower leaves of the grapevine canopy.

The economic impact of Rotbrenner is significant due to the loss of photosynthetic area, which directly reduces fruit sugar levels and overall vine vigor. To protect the vineyard, growers should focus on cultural practices such as removing leaf litter and ensuring canopy aeration. Chemical control, involving specific fungicides applied during the early growth stages, is vital for managing the disease in high-risk areas.