When to start spraying?

[GreenEnvy22]

I'm in the Niagara region, and have a couple dozen muscat vines plus some riesling.
The muscat are generally ok with disease, but the riesling had black rot bad last year.

Still just have buds pushing so far, nothing opening up yet.

When do I want to do my first spray? Some directions talk about first bloom, some say bud-opening.

I have a few fungicides available: Kumulus DF, Manzate Pro-stick, Pristine, and Switch 62.5.

Mostly want to control black rot and later on mildew.

 

[balatonwine]

When do I want to do my first spray? Some directions talk about first bloom, some say bud-opening.

Both are correct. It is simply that the most "critical" period is just before bloom and up to 4 weeks after bloom, as this is when the chance of infection (and later damage), if it will occur, will happen. So if you can only spay a little, that is the time to do it.

See the below document for a full spray schedule plan for many different spray chemicals. This is a "safe" full spray schedule -- do that and you are probably okay - but it takes the most work and most money. Normally, you modify the schedule depending on your needs and that may change every year depending on weather. And that you have to either figure out, often from experience or by following a monitoring program, or asking a local grower what they spray and when.

https://kb.osu.edu/dspace/bitstream/handle/1811/56335/OARDC_HCS_0744_paper_04_Ellis.pdf?seq

 

[BigH]

The midwest fruit and tree spray guide says to start spraying for black rot when shoots are 1 to 3 inches in length. Granted, you are not exactly in the midwest.

H

 

[balatonwine]

The midwest fruit and tree spray guide says to start spraying for black rot when shoots are 1 to 3 inches in length.

The link I provided says 1 inch. So we pretty much match.