It is a translaminar fungicide not a systemic, there is a difference. Application rate is 10-30ml per gallon. I've been doing roughly 2 tbsp per gal for foliar and my plants are doing great with no signs of PM or mold.
If you have access to giant knotweed you could easily make your own.
Active ingredient is called "Resveratrol" same stuff in anti aging beauty products. You can easily find it in bulk powder form online. If someone is courageous the only other step would be figuring out the rate of resveratrol dry powder to H20. You can also of course use giant knotweed and make a tea, at the end of the day resveratrol is the active ingredient that allows giant knotweed and regalia to prevent Fubgus spores so well.
In a University of California Davis Agriculture School study they used regalia alone, regalia with another OMRI biofungicide, chemical fungicide, and no fungicide at all.
To my recollection crops with just regalia lost around 10% of harvest. Crops with both regalia and a second BioFungicide lost around 5% total yield. While crops without any lost about 30-40% total yield. Those crops with chemical Fungicide lost 5% or less. I'm really giving a guess on the numbers here, I'm not interested in finding this article again. The point I wanted to make is about the efficacy of Regalia alone. It is a seriously great product and with use of other biofungicides can provide almost identical protection to that of a chemical Fungicides like Eagle 20.
This company has the worst customer service ever. No one ever answers no one emails you back ever. Their product is almost a hundred dollars a gallon. But no one can answer if this product burns or discolors the flowers. Maybe someone here knows
It is OMRI rated but I would never put it on flowering plants loaded with pistils, just personal choice. Maybe isolate one plant and try it if you are concerned isolate a lesser plant and see for yourself I'd love to know answer.
I personally don't even use compost tea sprays on plants with pistils and opt for root feeding compost teas.