Dothiorella grapevine decline

The primary symptom is the appearance of specific spots on one-year-old shoots, which darken over time, turning brown or brownish, often surrounded by a lighter halo.

Affected bark in areas where the fungus develops gradually dies off, becomes brittle, and may crack, exposing the internal tissues of the vine, which disrupts the normal flow of sap.

At later stages of infection, weakened shoot growth, premature yellowing, and leaf drop are observed, and in severe cases, partial or total dieback of the cordons occurs.

When examining a cross-section of the vine, one can notice characteristic browning or necrosis of the wood, which indicates deep penetration of the fungal mycelium into the vascular system.

Sometimes, small black dots — the fungus pycnidia — can be seen on the surface of dead bark, which serves as an important diagnostic sign for identifying the pathogen.

The causal agent of this disease is the fungus Dothiorella sarmentorum, which belongs to the class of ascomycetes and is known as one of the factors causing grapevine wood necrosis.

This microscopic pathogen can persist for long periods in plant debris, infected shoots, and vine bark, waiting for favorable conditions to begin active reproduction.

The life cycle of the fungus includes the formation of pycnidia — fruiting bodies where spores mature, which easily spread via raindrops or wind gusts throughout the entire vineyard.

The pathogen primarily penetrates plant tissues through bark damage, pruning cuts, frost cracks, or wounds caused by insect pests.

Biologically, Dothiorella sarmentorum is closely associated with the complex of grapevine trunk diseases, making it a difficult and dangerous component of vine infection.

The disease develops most intensely under conditions of high humidity and moderately warm temperatures, which are ideal for spore germination.

Weakened vines that have suffered from drought stress, excessive soil moisture, or winter frost become more susceptible to colonization by this pathogen.

Poor agricultural practices, such as incorrect pruning without subsequent tool disinfection, create entry points for rapid infection of the grape tissues.

Crowded plantings with poor air circulation contribute to moisture retention, which significantly increases the risk of fungal disease spread within the vineyard.

Imbalanced plant nutrition, especially an excess of nitrogen fertilizers, reduces the natural resistance of the vine, making its tissues softer and more vulnerable to mycelium.

The main danger is that the fungus causes systemic damage to the vascular system, leading to gradual degradation and death of individual cordons or the entire vine.

The yield of infected plants drops sharply due to the lack of nutrients; berries become smaller, lose sugar content, and fail to reach their market standards.

The disease is often latent, so visual signs usually manifest only when the tissue damage process has become irreversible, requiring the removal of significant parts of the vine.

The spread of Dothiorella in a vineyard leads to significant economic losses, requiring the replacement of entire vine rows and a long period of plantation recovery.

• Reduction of vineyard longevity
• Loss of productive cordons
• Decline in wine production quality

The fundamental control measure is timely sanitary pruning and the removal of all infected parts of the vine, followed by mandatory burning outside the vineyard to destroy infection sources.

Pruning tools must be regularly disinfected with alcohol solutions or special antiseptics after working with each vine to avoid transferring fungal spores.

An effective technique is sealing large pruning wounds with grafting wax or using copper-based products immediately after pruning to protect the wounds from fungal entry.

Preventive fungicide spraying during the growing season helps reduce the overall infection pressure, although no highly specific treatments for Dothiorella currently exist.

Maintaining high standards of viticulture, ensuring good canopy ventilation, and balanced application of mineral fertilizers strengthen the vine's immunity against wood diseases.