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.
Can someone advise on how best to treat blackspot forming on some v ery young rooted cuttings? I took a hand at rooting an old climber and they took, but now I am seeing the begining of black spot on a leaf or two. I have been keeping them outdoors but will need to overwinter these under my grow lights in the basement within 2 weeks (zone6b). Thanks for the suggestions and advice.
Welcome to the forum Mike. Mancozeb or Daconil are the best contact fungicides used to control blackspot. Since you will be growing your cuttings indoors, Daconil is much easier to purchase in smaller amounts. Dithane is another form of Mancozeb. I buy 6 pound bags of Manzate Pro T&O, but you probably don’t need such a big bag (I spray several large rose gardens.).
Once your cutting leaves are kept dry you shouldn’t see further blackspot growth.
Thank you for that advice, Sheree.I have some Daconil and Mancozeb, so i will make a small batch and spray the cuttings. Supposed to freeze tonight so I will bring them into the garage overnight and return outside tomorrow to take on the last week of decent weather before moving them indoors. I wish I had 3 gardens to tend! On a seperatge note, can you advise what I should spray for protection as we transition into late fall and early winter for my outdoor roses? I have 28 plants I tend to and want to keep the blackspot at bay. Only had 1 plant that got blackspot and early fall it began to spread to a few nearby bushes, but the majority remained disease free all season long.