Bordeaux mixture is primarily used to prevent outbreaks of which vine disease?

Bordeaux mixture is primarily used to prevent outbreaks of which vine disease?

• A. Powdery Mildew.
• B. Downy Mildew.
• C. Phylloxera.
• D. Botrytis.

Answer: (B)

Bordeaux mixture is a copper-based preventive spray developed to keep grapevines from contracting downy mildew. Mixing copper sulfate with lime creates copper compounds on the leaf surface that act as a contact fungicide, blocking the germination and early growth of the oomycete Plasmopara viticola, the organism that causes downy mildew. Because it works by contact, it’s most effective when applied before infection and with thorough coverage; rain can wash it away, so timing and reapplication matter. Downy mildew thrives in wet conditions, so this approach was historically a key defense for vineyards in damp climates. Powdery mildew is caused by a fungus and responds differently to treatments, while Phylloxera is an insect pest and Botrytis is a rot that requires other controls. So the disease Bordeaux mixture is designed to prevent is downy mildew.

Bordeaux mixture is a copper-based preventive spray developed to keep grapevines from contracting downy mildew. Mixing copper sulfate with lime creates copper compounds on the leaf surface that act as a contact fungicide, blocking the germination and early growth of the oomycete Plasmopara viticola, the organism that causes downy mildew. Because it works by contact, it’s most effective when applied before infection and with thorough coverage; rain can wash it away, so timing and reapplication matter. Downy mildew thrives in wet conditions, so this approach was historically a key defense for vineyards in damp climates. Powdery mildew is caused by a fungus and responds differently to treatments, while Phylloxera is an insect pest and Botrytis is a rot that requires other controls. So the disease Bordeaux mixture is designed to prevent is downy mildew.