Mildew on grape vine

Asked September 7, 2018, 2:39 PM EDT

How to rid mildew from grapevine?

Denver County Colorado

1 Response

The best control is prevention and there are a number of options. All need to be reapplied after it rains or the vines get wet.

Here is the Extension fact sheet on powdery mildew:

There are some treatments for the mildew, which also last a short time.

Controlling or Eliminating Powdery Mildew - Growing A Greener World®

Spray on plants every one to two weeks. Potassium bicarbonate– Similar to baking soda, this has the unique advantage of actually eliminating powdery mildew once it's there. Potassium bicarbonate is a contact fungicide which kills the powdery mildew spores quickly. In addition, it's approved for use inorganic growing.

Organic Ways to Kill and Prevent White Powdery Mildew | Dengarden › Gardening › Garden Pest Control
Jul 23, 2018 - The acetic acid in apple cider vinegar is very effective in killing powdery mildew. Take care to not make the mixture too strong as the acidity of the vinegar can burn plant leaves. Mix 4 tbsp. of vinegar (5% solution) with 1 gallon of water. Reapply every three days.

The site above also has a long list of preventatives. All of these treatments are rather labor-intensive.

Powdery mildew can slow the growth of or even kill your plants, if severe enough.

Preventions also includes not overhead-watering and keeping air circulating (do not crowd plants).

Hot, dry weather encourages the growth of powdery mildew.

Best of luck