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Handy Andy

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I had problems last year due to Mildew, and am spraying this year to prevent problems.

How often do other people spray, against mildew? Is it normal to spray throughout the entire growing season?

The sprays I am using state "spray every 10 to 12 days" against Powdery and Downy Mildew.

Do I need to spray now that my vines are looking healthy?
 

wood1954

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Spray now and after heavy rain or about every ten days, very important if you live in a humid area
 

balatonwine

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Do I need to spray now that my vines are looking healthy?
Spraying is a preventative measure.

If you see damage, then it is too late. The damage is done, and spraying will not undo the damage. In fact the damage will often only get worse even if you spray immediately after seeing damage.

As for when to spray, a routine is most effective, but also costly. There are alternative methods depending on where you live what diseases you are spraying against, such as calculating a risk index:

 

Handy Andy

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Spray now and after heavy rain or about every ten days, very important if you live in a humid area
Mid atlantic is humid and warm, but at the moment mostly less than 70F 21C at least for another 2 or 3 weeks.

Spraying is a preventative measure.

If you see damage, then it is too late. The damage is done, and spraying will not undo the damage. In fact the damage will often only get worse even if you spray immediately after seeing damage.

As for when to spray, a routine is most effective, but also costly. There are alternative methods depending on where you live what diseases you are spraying against, such as calculating a risk index:

I arrived here last year, in May due to Covid restrictions just as the first signs of Mildew were starting. The temperature then reached daily 18C to 25C. At the moment we are typically getting 15C to 18C daily.

Thanks for the link! If I am reading it correctly I am at low risk at the moment, but will likely have problems if I stop spray in 2 or 3 weeks time, as the weather warms up.
 

Neb Farmer

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I live in a humid area of the Pacific Northwest, and mildew is always something to guard against here. I spray wettable sulphur every 2 weeks starting before buds appear, when buds appear, at bud 'break' and then every 2 weeks UNTIL about 5 weeks before harvest. You don't want a bunch of sulphur on your harvested grapes, so i stop spraying right about then. AFTER harvest I will usually start spraying again , every 2 weeks until hard winter weather comes. Then i hold off untill weather warms a bit again in the Spring.
If it 'rains off' I will re-apply the sulphur a little earlier than usual.
 

Neb Farmer

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Mildew will hide in the bark of grapevines, and once you've had a mildew problem you most likely will always have a presence of mildew. You *can* spray a fungicide to kill mildew spores, but usually the thing to do is preventative measures....spraying sulphur or another type of chemical that 'retards' or prevents mildew growth.
IF YOU DON'T spray for mildew, mildew can not only damage the leaves and vines, it can damage the the grapes themselves, causing incomplete growth . The grapes can literally stop growing when small bb-sized , turning hard, juiceless, and not much good for anything. You don't want that, trust me! lol
So, preventative is the way to go. My opinion, of course, but I received my information first hand from local professional grape-growing-wine-making guys.
 

Phil

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I just plant about 200 vines and they starting to shut out do I need to spray the first year
Thank you
 

mbrssmd

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Everyone's climate situation is different, as is time/labor availability. But for what its worth...

While I've always sprayed regularly, I only began experiencing some noticeable success in keeping the nasty mildew brothers in check by becoming obsessive with keeping good airflow -- which occasionally means being downright ruthless in shoot-thinning and leaf-pulling.

By late July in some places I'm to the point of counting leaves per cluster. I tend to do that out loud, complete with pointing so that anyone driving by can go home and tell how they saw a crazy old guy arguing with his grapevines.
 

Phil

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Thanks for your input
If I may ask what kind of chemical you use .I live in the foothills of Nc mountain and I grow Vinifera
What kind of grapes you plant
Thank you
 

mbrssmd

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Thanks for your input
If I may ask what kind of chemical you use .I live in the foothills of Nc mountain and I grow Vinifera
What kind of grapes you plant
Thank you
I grow vinifera as well: Barbera, Cab Franc, and Petit Verdot, about 140 vines total. I use Mancozeb plus Stylet Oil for the first 2 or 3 sprays, then switch to Mancozeb plus sulfer. After 5 sprays with Mancozeb I switch to Captan plus sulfer (to avoid resistance).
 

Phil

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Did you spray on the first year
Or start the second year
Thank you
 

mbrssmd

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Spraying in first year is important to get them off to a good start, at least in our east coast climates. I DM'd you with a paper from U Md extension I found helpful when I was starting out.
 

Handy Andy

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which occasionally means being downright ruthless in shoot-thinning and leaf-pulling.
What do you mean by "ruthless in shoot-thinning and leaf-pulling" How many shoots and leaves do you leave behind.
 

Obbnw

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What do you mean by "ruthless in shoot-thinning and leaf-pulling" How many shoots and leaves do you leave behind.
last year I was ruthless and thoughtless.....

I started early, got carried away and significantly reduced harvest quantities on about half my vines. No mildew though ; ).

I'll pay more attention this year to what is setting fruit. I don't have a traditional trellis - closest thing is a pergola, so the "fruiting zone" is not as obvious .
 

Phil

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What does it mean Captan plus Sulfer or Mancozeb plus sulfer
I know both of them but sulfer not sure
 

wood1954

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Sulfur is an element, it comes as a powder you mix with water. It does burn some grapes so you need to check that out. Look up grape sensitivity to sulfur you should get a lot of info.
 

Phil

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Thank you
I mostly got Rhône variety and I check on it
Does your spray schedule work for you
 
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