powdery mildew on grapes

[DigitalVinyl]

We've had some very hot humid weather in the northeast, and I've developed some powdery mildew on a small section of the vine.

I can see the whitish hairy grpwth on a section of leaves. I'm wondering if it too late to control it.

What has been most effective for home gardeners treating an existing infection?? I see wettable sulphur mentioned being applied to acres, but often the home gardeners has choices commercial growers can't use (like picking bugs off rather than blanketing the area in pesticides)

Does cleaning the leaves off help control the infection? I would imagine that the physical mildew impedes photosynthesis some, which would reduce the health and vigor of that leaf/vine--helping the mildew to survive.

Do you remove the diseased leaves? I'm guessing it is something that can spread so less of it is a control.

I see some on grape clusters too. I'm planning to remove those--I have plenty of other clusters.

I am concerned that some of the berries are almost 1/4" round, but most are still smaller. There are warnings about using the wettable sulphur, especially with table grapes--which these are.

DiGiTAL ViNYL (no email) Zone 6b/7, Westchester Co, NY,

[Paul E. Lehmann]

me know if you try it and how it works for you.

[Mike]

I had some white powder on my parlor palm until recently when I added a nickel-size portion of dish detergent to the gallon-plus watering can and basically showered it. Rubbing the leaves free of dust etc.to allow photosynthesis. Appears to work; be sure to rinse with clear water.

Disclaimer: also did it one time with some ground cover - looked great but then disappeared. Could've been from chemicals, shifting sun, or lack of water. Dunno.

Mercenary gardener, z11

[bamboo]

Whitish hairy growth sounds more like gray mold to me. I'd be removing affected leaves if possible. You do not cure fungal disease you prevent it. This time of year I'd be expecting a lot of black rot as well.

[DigitalVinyl]

A little update.

When I spotted PM it was after two scorching weeks of heat and a dry month. I was surprised that this weather INHIBITS pwdery mildew, makes sense it is a MILDEW! And yet it was after that that I noticed it growing.

Well the last week was humid warm and daily downpours late in the day. The humidity should benefit the PM. Over 85 degrees inhibits it.

Last weekend I treated the grapes with a weak solution(2 gallons water) of baking soda(1 1/2 tsp) and milk(skim, 1 cup). There are other plants that would get drenched by this solution so I didn't want to do anything extreme. You also can't just keep using the baking soda cause it will affect the soil. I also hand cleaned the worst leaves.

Today I inspected them, then treated them again. This time 2 gallons water, 1 1/2 cup skim milk, 2 tsp baking soda

I have to say the amount is noticeably less, but still there. I still see it obviously on some grape clusters. I can't clean them only trash them. I left them to measure progress on them. This week I made sure to go under the leaf canopy and wet individual clusters with the solution.

There's no way to know if this treatment really kills it or the hot summer does.

DigitalV>We've had some very hot humid weather in the northeast, and I've

Zone 6b/7, Westchester Co, NY,

[Tom Jaszewski]

There IS good data on milk as a control.

1 part milk and 9 parts water. Whey proved to be more effective. I spray with a mist blower and get adequate control on ornamentals.

[Paul E. Lehmann]

Do you have any idea if milk has any effect on other fungus such as black rot or downy mildew. I have read that it is only good on Powdery mildew but would like some feedback if others have had success with other fungus.

[Tom Jaszewski]