June, Roses, and Summer weather

My first rose on this plant and it's a beauty! Taken in the early morning light so nice petal details really show up.
 Here on the Oregon coast, we have iffy summer weather in June. Generally we don't really get the summer days and heat until July so a few days of gorgeous unadulterated sunshine and warmth is a real treat!
 Problem with roses and our typical mild wet weather is fungal disease. It makes me just want to cry to see the leaves all turn black and fall off. So, I knew that baking soda in a solution helped, so I did a google search for a formula and here it is:

The Baking Soda-Vinegar Formula

1½ tablespoons baking soda
2 tablespoons vegetable oil
1½ tablespoons Safer Insecticidal Soap (or liquid, not dish, soap)
1 gallon water
1 tablespoon vinegar
Mix together the baking soda, oil, soap, and water. STIR in the vinegar last - don't shake! Pour into a no-clog type hose-end sprayer. If you only have a couple of roses to treat use a hand-held spray bottle. Spray in the morning and when the temperature is less than 80 degrees. Thoroughly soak all parts of the plant. Apply weekly as needed.

If you remember your high school chemistry, when you mix an acid (vinegar) and a base (baking soda) they cancel each other out and you get water that has a neutral pH. So the question is, how does this formula work to kill mildew?

When baking soda and vinegar are mixed they produce water, carbon dioxide (which bubbles away), and sodium acetate (which stays in solution). I found many references to sodium diacetate as a mold and mildew inhibitor in baked goods and some references to sodium acetate as a fungicide. Apparently, the active ingredient of the baking soda-vinegar solution is the sodium acetate.

The Vinegar Rinse

2 tablespoons white or cider vinegar (5 percent)
1 gallon water
Pour undiluted vinegar into the container of a dial-a-spray hose-end sprayer. Set the dial to deliver 2 tablespoons per gallon and start spraying. Soak the entire plant, making sure to get the undersides of the leaves. Spray only in the morning. Apply once a week as needed until the weather warms up.

recipes found at Good Earth Organic Rose Care
nice site with a ton of rose information, recommended!