Powdery Mildew on grape vines?

Question

I have 2 grape vines growing in my greenhouse & they are beginning to have a powdery mildew on them. Does any one know what this might be & how I could treat them?

Answer 1

too dry at roots and not enough pruning in winter so that airflow is too slow around plant.Each pruning leave 3 main horizontals and cut back all side stems to 2 buds.You will get more fruit less leaves and more open vine and hopefully less mildew.

Answer 2

The organic grower is going to take into consideration things such as: the location of the vineyard, design of vineyard, row orientation, choice of variety of grape (due to susceptibility factors), canopy structure, irrigation, water and nutrition and shoot removal done early in the season.

There are chemical treatments that can be used as well to help treat and get rid of the powdery mildew. The application of fungicides should start with early shoot growth and continue until bloom. It is important to establish good control early so that the disease is prevented from becoming the powdery mildew epidemic of the summer. Fungicides that are used most often include sulphur, Nova, Lance, Sovran, Flint or Milstop.

Doing a dormant spray of lime sulphur is very effective when it comes to suppressing any over wintering population of the mildew. Applying in the early spring before the buds break will kill the powdery mildew, covering any dormant vines is very important. Then there is the post-harvest spray. These are also beneficial, and the date of your harvest will help you determine the necessity to keep foliage and canes protected.

There are some cultural things that you can do to help control the disease and possibly prevent it. Make sure that you are selecting proper rootstocks, training systems and fertility. Make sure that you are practicing timely sucker control. Cut the canes back close to the top wire of the trellises. Make sure that you are removing leaves so that bunch rot does not occur, this allows the fungicides to better cover the clusters. You can also choose one of the very few grapes that are not susceptible to this fungus to grow the grapes that are not susceptible such as Auxerrois, Malvoisie, Melon, Pinot Gris and Semillon.

Choose carefully, plan wisely and spray at the appropriate times to make sure that the powdery mildew does not attack and destroy your crop.

Good Luck with them.

Answer 3

comes with the turf, as I understand it!

Answer 4

You might just find it's natural yeast.

Answer 5

too wet and too dark spray with a mixture of baking soda and water,decrease watering and its called powdery mildew

Answer 6

Apply fungicides as soon as the problem is identified.  Next year, apply a fungicide just before the start of hot, humid weather in your area. Affected areas of leaves will not be cleaned of the white mildew. But, it stops the spread of the disease, and kills the existing mildew. Regular treatment with fungicide is recommended.

If the affected area is minimal, you can remove unsightly, affected leaves. If the disease has affected a large percentage of the leaves, removal of all of them may affect the growth of the vines, but ridding the vines of as many affected leaves as possible is your best bet.