I have one rose plant (of 8) with black spot. The rose is over 100 years old and we want to keep it as healthy as possible. A nursery told us today to use mancozeb, then a week later Propiconazole, repeat the two steps one more round a week apart, then half strength propiconazole every 3 weeks.
does this sound right?
I can’t find anything but 6pound bags of dry mancozeb. Where do you all find it? No where local comes up in searches (around Nashville, TN)
Welcome to the forum. Their recommendation is good, however Mancozeb only lasts on your rose leaves for about 5 days. It is a contact fungicide and has no residual properties. Propiconazole is a good systemic fungicide that lasts about 10 days and is Preventative. I prefer to combine both Mancozeb and Propiconazole in the same spray tank, with a spreader sticker (Souther Ag’s Tweak, aka Indicate 5). This has the advantage of preventing fungicide resistance to the Propiconazole. You can buy Manzate Pro-Stick T&O from Amazon for $32.79 which a very low price, a true bargain.
Pre mix the Mancozeb in a separate container to ensure it dissolves, it is prone to clumping. When you are finished with the Propiconazole get some Eagle which is concentrated Myclobutanil. It is also effective against Powdery Mildew, and cheaper than Propiconazole. I also add the seaweed product, Maxicrop, it improves the health of your roses.