I have two roses growing in large pots and they survived the winter with lots of leafs still on the plant. Three of the canes and many leafs was full of milldue. I did use some spray i found at the gardencenter but it still was there and worse. Then I cut of the worst affected leafs and treated the canes with olive leaf extract in some water.

I used one capsual of oliveleaf extract (the kind you can by at healthfood stores.) and added two teaspoons of water and pencilled the green liqud on the affected areas with a paint brush. I am positive that one or two capsuals of oliveleaf extract into a litre of water will work very well as a spray too.

Now it is a month after the treatment and all milldue is still gone. All traces of milldue was gone in one or two days after first treatment. I sprayed the plants with olivleaf extract (one capsual to 1/2 litre of water) after three days just to be on the safe side. No damage to the healthy leafs.

It is expensive to by olivleaf extract but a bottle contains 30 or 60 capsuals and if one capsual is enough for one spraying its not too bad. It worked much better than grapefuitseed extract and any spray I have bought at the gardencenter.

I hope this little discovery of mine will work just as effective the next time milldue appears. This should really be tested more systematic. Has anybody else tried this ? It seems to work very quickly, improvment is instantly and after a day or two all traces of milldue is gone.