How to Get Rid of Mildew on Grapes

This is the second part to a recent article I wrote explaining one of the most problematic areas about growing grapes is Downy Mildew, the white powdery substance that tends to take over grapes, sometimes even destroying the crop. I explained the causes of downy mildew as well as the history and cure. In this article I will be looking at management as well as the best ways to get rid of this horrible fungus.

Management

If at all possible select a variety of grape that is powdery mildew resistant.
Plant in full sun in a well drained area.
If your plant is potted try to move it outdoors as this will give it better airflow.
Do not overcrowd.
Have good airflow and ventilation.
Fertilize but do not over fertilize, this type of mildew thrives where there is high nitrogen sources.
Prune any infected area. This will not only remove infected areas but increases airflow and sunlight to the plant.
Keep plants in the sunlight.
Disinfect your garden tools with one part bleach and 4 parts water after each use.

(Try to remember this type of mildew is sensitive airflow, extreme heat and direct sunlight.)

Treatment Though Fungicides

Applications of lime sulfur and sulfur dust should begin at the first sign of mildew and should repeated as necessary. If your vine has had mildew on it the previous year, it is usually best to spray with lime sulfur while it is dormant as this will get rid of any over wintering spores. Also to eradicate the mildew begin the process of spraying or dusting early with the first sign of shoot growth or when the buds open and repeat spraying or dusting until bloom. Always spray at the appropriate times usually 1- 2 weeks between applications.

Though fungicides are an effective way to control mildew and this method is most often used on commercial grapes many gardeners, including myself, tend to try and avoid the usage of chemicals on plants with fruits and vegetables simply because no one really likes the thought of actually consuming something that was just sprayed with chemicals. If your looking for a safer more organic way to achieve the same effects but without the chemicals try using garlic as it contains naturally high levels of sulfur. By crushing a few cloves and adding it with water you will have an effective homemade sulfur spray.

When using any kind of fungicide, in order to be successful in controlling the mildew, you must spray at the first sign of infection.

Treatments By Using Natural Methods

There has been much study placed into 3 bi-carbonates, sodium, ammonium and potassium and all were effective, however; since excess sodium and nitrogen are problematic in grapes only, potassium bi-carbonate alone was selected to be studied. Potassium bi-carbonate was not only found to be safe for usage but also was found to be as effective as wettable sulfur.