Blight spreads fast, as you know. Remove diseased leaves using care to not spread it around (gardening gloves and clean shears.) Also cut off bottom leaves near soil line. (Don't compost it, burn the garbage.)
Treat with copper based fungicide. The stuff we sell is listed organic. It will only retard the spread. Malicious fungus is next to impossible to stop once it has started.
As prevention, I would say make sure the soil is fully fortified (rock dust, nutrients, compost.) One big thing you could do is right back to the compost tea. and I would actually use the same recipe to crank up your huckleberries.
I call this "fungi dominant compost tea" because we're basically growing beneficial fungi suspended in solution to out compete the bad fungi (mildew, blight, etc.) It will also help form symbiotic relationships with your woody trees/bushes/berries.
Take a 5 gallon bucket, fit it with a small $10 air pump and air stone. Your tea brewer is now constructed.
Take 1/2 cup earthworm castings or high quality compost (most important ingredient), mix with 1/2 cup dry oats (the kind you make oatmeal with.) Moisten it, and wring it out to field capacity (you can squeeze and maybe get 1-2 drops of water dripping off.) Wrap it in newspaper and place it in a warm, moist place like a broom closet. Don't seal it up, it needs air. Leave it for 3-4 days. When you open it up, it should be covered in a beautiful white fungus that smells like freshly cut mushrooms.
Take this, place into a pantyhose/cheesecloth bag, hang it into the bucket. Go find some de-chlorinated water (grocery store or water filter. de-chlorinated is very important.) Fill the bucket so the wad of castings/oats are covered in water. Add a few tablespoons of kelp (dry or liquid is fine.) Additionally you can add some humic acid, yucca, and/or rock dust. Turn on your air pump and let this whole thing bubble for 24-30 hours out of direct sun.
It should smell like fertile soil when it's finished. Dilute this to a few tablespoons a gallon to a few cups. You can't burn/overdo this. Spray it/water it everywhere. It will help nearly everything in nearly every way. What you just brewed is a SUPER concentrated compost solution.