This rose has already significant Blackspot so early in our season. Not a good sign!
Today I used a spray mixed from a recipe of the Rosarium of Winschoten: for every 5 liter=>
10 grams of magnesiasulphate
10 grams of spraying-sulphur
10 grams of Algeco (concentrated Algae-extract)
35 ml of Vital (a leaf fertilizer)
25 grams of baking soda
25 ml of sunseedoil
1.25 ml of (dishwashing) detergent
8 ml of sodiumsilicate (because some roses became powdery mildew from the surrounding big oaks)
Dissolve in 5 liters of water (about 40 degrees C)