Grape anthracnose

Early symptoms manifest as small, dark, circular spots on young shoots and leaves, which progressively enlarge and deepen into lesions.

A hallmark sign of this disease is the development of sunken cankers with dark brown or black margins, often leading to shoot deformation or cracking.

Berries develop the characteristic "bird's eye" lesions: round spots with a pale gray center surrounded by a dark reddish-brown border.

Leaves may show angular or circular spots that often become brittle and tear, resulting in a ragged appearance of the canopy.

Severe infestations lead to stunted growth, wilting of flower clusters, and significant premature defoliation, which hampers the vine's development.

The causative agent of this disease is the fungus Gloeosporium thuemenii (synonym Gloeosporium ampelophagum, anamorph of Elsinoe ampelina). This fungus is a serious threat to viticulture worldwide.

The pathogen overwinters as mycelium and sclerotia within the infected tissues of vines, bark crevices, and mummified berries left on the vineyard floor.

In spring, the pathogen activates when temperatures rise and humidity increases, spreading its conidia through rain splashes and wind currents to nearby host plants.

The fungus is highly aggressive, capable of infecting almost all green parts of the vine, including leaves, shoots, flowers, and developing berries.

Its complex life cycle requires diligent monitoring and early intervention, as the fungus can remain latent until the right climatic triggers appear.

High relative humidity and frequent rainfall are the primary catalysts for the rapid germination of conidia and the establishment of new infection sites.

The optimal temperature range for the pathogen's growth is between +15°C and +25°C, making spring and early summer the most critical periods for protection.

Poor vineyard management, such as lack of pruning and excessive canopy density, promotes high humidity and prevents airflow, fostering the disease.

Vineyards located in low-lying areas or close to stagnant water sources are at higher risk due to prolonged periods of morning dew and fog.

The accumulation of debris and organic matter around the base of the vines provides a protected environment for the pathogen to thrive throughout the year.

The economic impact of this disease is substantial, primarily due to the loss of marketable yield caused by berry shriveling and rotting.

Affected vines show decreased vigor and poor wood maturation, which significantly lowers their survival rate during harsh winter conditions.

Infected shoots are structurally weakened, making them susceptible to breakage and reducing the number of productive buds for the next season.

The constant need for fungicide applications increases production costs and may impact the overall ecological balance of the vineyard.

Failure to control the disease can result in the rapid decline of sensitive grape varieties, potentially requiring the removal and replanting of entire vineyard sections.

Effective management begins with strict sanitation: pruning infected canes and removing all dead plant material from the vineyard site.

Improving canopy ventilation through proper shoot positioning and leaf thinning is essential to reduce humidity levels around the fruiting zone.

Proactive spray programs using copper-based contact fungicides and systemic treatments are necessary during the active growth phases.

Applying dormant sprays early in the spring helps eliminate the overwintering inoculum before the new season begins.

• Planting resistant or tolerant cultivars where possible.
• Balanced fertilization to optimize vine tissue strength.
• Regular scouting for early detection of symptomatic lesions.