Downy mildew (Plasmopara viticola) can be easily be confused with another common plant disease called powdery mildew. While powdery mildew is cause by a true fungus, downy mildew is cause by parasitic organisms that are more closely related to algae. Because it is closely related to algae, downy mildew needs moisture and cooler temperatures to survive and spread.
Downy Mildew appears as yellow to white patches on the upper surfaces of older leaves. On the undersides, these areas are covered with white or grayish, cotton-like fungi. These “downy” masses are most often noticed after rain or heavy dew and disappear soon after sunny weather resumes. As the disease progresses leaves may eventually turn crisp and brown and fall off even though the plant has ample water.
In order to treat and manage downy mildew, use any of the natural treatments listed below. The treatment selected should be added to a spray bottle and applied to the leaves of the affected plant for three consecutive days. If no results are shown after two weeks of completing the treatment and the disease continues to spread, you may try another one of the remedies listed below. Do not apply the treatment while the plant is receiving full sun, apply early in the morning or after sunset.
1 cup of chamomile tea combined with 2 cups of water
1 tablespoon of cinnamon combined with 1 liter of water
5 cloves of garlic combined with 1 liter of water, place mixture in a blender for best results
1 tablespoon of baking soda combined with 1 liter of water
1 tablespoon of vinegar combined with 1 liter of water
1 cup of milk combined with 1 cup of water
For More Advanced Cases
combine 800 ml of water with 200 ml of milk and 20 g of baking soda