Grape pests and diseases: Biological control

Downy mildew in grapes

Grape downy mildew (Plasmopara viticola) is one of the most destructive diseases in grape production, particularly under humid and wet conditions. The pathogen infects green tissues and can spread rapidly, leading to significant yield and quality losses if not controlled early.

Symptoms and impact

• Yellow “oil spots” on the upper leaf surface
• White, downy sporulation on the underside of leaves
• Infection of young shoots and bunches
• Premature leaf drop and reduced photosynthesis
• Severe cases: crop loss and reduced vine vigor in the following season

Disease development

Downy mildew thrives when:

• Leaf wetness duration is high (rain, dew, irrigation)
• Temperatures range between 10–25°C
• Dense canopies reduce airflow and prolong moisture

Biological control of downy mildew in grapes

Tiagan is designed to support control of grape downy mildew (Plasmopara viticola) within an integrated crop protection strategy. It works by interfering with disease development and reducing infection pressure, helping to protect new plant growth during critical stages.

Tiagan is based on the free-living amoeba Willaertia magna C2c Maky is known for its ability to produce a wide range of bio-active compounds involved in microbial interactions. When used as a lysate, these compounds support plant protection by acting both on the plant surface and by activating the plant’s natural defense mechanisms. This dual mode of action makes Willaertia magna–based solutions well suited for the preventive management of grape downy mildew.

Powdery mildew in grapes

Grapevine powdery mildew (Erysiphe necator) is one of the most widespread and economically significant diseases in grape production. Unlike many fungal pathogens, it does not require free water to infect, making it a persistent threat throughout the growing season, especially in moderate temperatures and dense canopies.

Symptoms and impact

• White, powdery fungal growth on leaves, shoots, and berries
• Reduced photosynthesis due to leaf coverage
• Berries may crack, deform, or fail to develop properly
• Lower fruit quality, affecting both yield and marketability

Disease development

Powdery mildew develops rapidly under:

• Temperatures between 20–30°C
• High humidity (but not necessarily free water)
• Shaded or dense canopies with limited airflow

Because spores can germinate without leaf wetness, infections can occur early and continuously, requiring a strong preventive strategy.

Control of grapevine powdery mildew

Effective control of grapevine powdery mildew requires a preventive and integrated approach, combining direct disease control with plant resilience.

• CeraSulfur: Acts through contact to inhibit spore germination and stop disease development. It forms the backbone of a preventive spray strategy, especially during periods of active growth.
• Tiagan: Supports disease control by reducing infection pressure and interfering with disease development, helping to maintain protection under varying conditions.
• Lumiere: Enhances plant vitality and resilience, supporting the crop in coping with disease pressure and improving overall performance under stress conditions.

Leafhoppers in grapes

Leafhoppers are common in vineyards and can cause significant damage by feeding on leaf tissue, reducing photosynthesis. Key species include Empoasca vitis (grape leafhopper), which causes leaf discoloration and reduced photosynthesis, and Scaphoideus titanus, a major vector of Flavescence dorée, a serious grapevine disease.

Symptoms and impact

• White or yellow stippling on leaves
• Leaf curling and premature leaf drop
• Reduced plant vigor and yield

Biological control strategy

• Lumiere: Supports control of sucking insects like leafhoppers within an IPM program