The Cornell Formula – baking soda based plant spray. Garden member L.M. shared this “spray-on plant disease preventative and fighter” formula developed at Cornell University. (There are many variations on this mix, but, this version has worked well for L.M. for 20+ years in her Pacific NorthWest gardens.)
To 1 gallon of water, add & mix:
1 tablespoon baking soda
1 tablespoon oil* (see website for more info on type of oil *)
1 or 2 drops dish washing liquid
* horticultural oil; may use vegetable oil in a pinch
Helps fight and prevent disease. Mix thoroughly; use sprayer. Remove dead and diseased parts of plant before spraying. Spray top and undersides of plant (leaves in particular) then apply fresh mulch. Discard (do not compost) removed plant materials. Do not spray in direct sun or heat of day. Do NOT use WD-40 or other weird oils!
For more details and the full, original article: https://www.gardensalive.com/product/yes-you-can-protect-your-roses-from-dread-diseases
Mike McGrath is the author of this article and info which was originally published in “The Philadelphia Daily News”.