Fungal disease
Grape Leaf Blight
Also known as Isariopsis leaf spot
A fungal leaf spot of grapevines that causes irregular dark brown patches, usually later in the season.
Symptoms
- Irregular dark red-brown to black spots on the leaves
- Spots merging into larger dead areas
- Early leaf drop on heavily affected vines
What causes it
The fungus survives on fallen leaves and spreads in warm, humid weather.
What you can do
- Clear fallen leaves and plant debris at the end of the season, where the disease survives winter.
- Train and thin the vine for good air flow.
- Water the soil, not the leaves, and water in the morning so any splashes dry quickly.
Not sure it's leaf blight?
Photograph one affected leaf and Plantulus will suggest the most likely problem, with a confidence score. It's free and needs no sign-up.
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General guidance only, not a diagnosis. Check product labels and local rules before using any treatment, and ask a horticultural specialist if a valuable plant is struggling. See the disclaimer.