Recently, I read information on your website reading "Mancozeb (simply the best against Black Spot once it has got going). " I ordered Mancozeb but there are no instructions on how to mix Mancozeb for Black Spot on Roses. What is your recommended mixture (i. e. ounces per gallon, etc. )?
Black Spot on Roses
I use 1 1/2 tablespoons per gallon when I spray my roses. You can use 2 tablespoons per gallon for a stronger mix if the black spot is real bad. It will leave a yellowish powdery residue on the foliage but that is part of how it work. Apply it again in 7 to 10 day intervals for at least three sprayings. Remember, once the black spot has left its mark on the foliage it is there to stay. However the mancozeb will kill the fungus and all new foliage that comes forth should be free of the black spot. If it is not, then repeat the applications of mancozeb at 7 day intervals at the 2 tablespoons to a gallon of water rate for 4 sprayings. Then follow up with two sprayings of either Immunox, Banner Maxx or Honor Guard.