Grape cane tannins

The action of these substances is based on their ability to form stable complexes with proteins and enzymes of harmful organisms. Upon contact, pathogen proteins denature, which leads to their death or a significant inhibition of growth.

Unlike classic fungicides, tannins act as systemic immunity inducers. They strengthen cell walls, making plant tissues denser and less vulnerable to mechanical penetration or enzymatic fungal attacks.

The mechanism also involves the chelation of metal ions, which pathogens require for normal metabolism. By depriving microorganisms of access to essential cofactors, tannins effectively slow the development of initial infection outbreaks.

This group of substances is characterized by low phytotoxicity, making them suitable as mild fungicides for disease prevention during the growing season and before harvest.

Tannins are primarily used against a broad spectrum of fungal diseases of grapevines, including downy mildew and powdery mildew.

They effectively suppress the development of gray mold (Botrytis cinerea), especially under high humidity conditions when berries are susceptible to infection.

The use of tannin-based products helps control the population of certain bacterial pathogens that cause leaf spot diseases.

These substances also serve as antioxidant agents to prevent physiological stress caused by unfavorable weather conditions.

• Powdery mildew pathogens
• Gray mold pathogens
• Complex of grapevine bacterial infections

Application rates for tannin-based products depend on the infection pressure and the vine's growth stage. Solutions are typically applied via fine-droplet spraying.

Initial treatments are conducted at the beginning of active shoot growth to establish a protective barrier. Subsequent treatments are performed at 10–14 day intervals depending on weather conditions.

During berry ripening, solution concentrations can be increased as these substances are safe for human consumption and do not require long pre-harvest intervals.

Special attention is paid to ensuring complete coverage of the leaf surface and grape clusters, as tannins function primarily through contact with spores and mycelium.

To enhance efficacy, the use of adjuvants is recommended to improve the adhesion of the preparation to the waxy layer of the grapevine leaves.

A major limitation is the dependence of efficacy on sunlight intensity and temperature, which can affect the oxidation rate of tannins.

It is not recommended to perform treatments during heavy rainfall, as rainwater can wash away the protective layer from the surface of the plant organs.

Mixing with highly alkaline preparations should be avoided, as changes in the solution's pH can cause active substances to precipitate, leading to reduced biological availability.

Despite their natural origin, it is essential to use personal protective equipment for the respiratory tract and skin when handling concentrated tannin extracts.

Storing working solutions for more than 24 hours is not advised, as polyphenol compounds are prone to rapid biodegradation and loss of protective properties.