Plant guide:ð Grapes
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Fungal
Downy Mildew on Grape Vines
Commonly affects: Vitis vinifera, V. labrusca (Grape)
Yellow, oily-looking patches appear on the upper leaf surface, with a white-grey downy growth on the underside directly beneath. Infected berries can shrivel and turn leathery brown.
Potential Causes
- 1Plasmopara viticola, a water mould that thrives in wet, humid conditions
- 2Rain or overhead irrigation providing the moisture the pathogen needs to spread
- 3Poor airflow keeping foliage wet longer
Solution Steps
- 1Remove and destroy affected leaves and fruit promptly
- 2Apply a copper-based or systemic fungicide preventively during wet periods
- 3Improve airflow through pruning and proper trellis training
- 4Avoid overhead irrigation, watering at the base instead
Prevention Tip
Downy mildew needs sustained leaf wetness to infect â anything that helps foliage dry faster (spacing, pruning, base watering) reduces risk significantly.
