Another Year, More Black Spot
Black spot on a rose leaf
Every season many rose gardeners battle a menacing nemesis called black spot, caused by the fungus Diplocarpon rosae – which can weaken or even kill rose in a relatively short time. Our C.R.’s have described the methods they enlist when fighting black spot in their gardens.
“I have a case of black spot in my garden at the present time. I am spraying it with Manzate, which is a powder form of a recommended fungicide. It must be mixed in HOT tap water and stirred until it is dissolved, before adding it to a spray container. The dilution is 1 tablespoon powder to 1 gallon of water. It lasts one week. I take care to spray over, under and around each plant. I have sprayed twice with this. The next spraying will be with Banner Maxx fungicide every three weeks. Check the ad in the American Rose Magazine, as these products can be ordered online from Rosemania.com”
- Pat Horbelt
“The #1 thing to remember about eliminating black spot is practicing sanitation in the rose bed. Pick off the diseased leaves (they will fall off anyway) so they won’t lay on the ground beneath the roses and cause more black spot. Then spray the rose bushes and the ground with Maneb or Mancozeb, and the spraying needs to be done before it gets to 85º degrees. Continue a spray regimen with alternating fungicides until the black spot is under control”
- Norma Kemp
“At present I am alternating between Mancozeb (available at Rosemania.com) and Bayer Disease Control for Roses, Flowers and Shrubs. Mancozeb is a contact product and the Bayer is a systemic. The Bayer product is fungicide only, not to be confused with their 3 in 1 systemic or All in One drench, which both deliver insecticide and fertilizer as well as fungicide. I believe it is important to vary the products used so that the black spot does not develop resistance to the product. Whatever strain of black spot I have (there are many different strains) became resistant to Banner Maxx after I used it exclusively for several years. I also occasionally use Neem Oil, a naturally derived product which will kill fungi and insects by smothering.”
- Betsy Latta
“I don’t spray anymore, I just follow good hygiene around the garden and try to choose resistant varieties.”
- Suja Mathew
“I spray with Mancozeb to treat roses for black spot. It will actually kill the spores. You will need to clean up around the base of the rose and remove as many of the diseased leaves as possible before spraying. Mix the Mancozeb in your sprayer using the directions on the bottle. Use personal protection, such as gloves, long sleeves and facial mask as needed. Spray top and bottom of the leaves, as well as the soil around the plant. Water the plant thoroughly before any spray treatments. You will need to repeat your spray routine once a week until you no longer see evidence of black spots”
- Mary Scheulen
“This may seem pretty drastic to many rose lovers, but I avoid spending all my time on my roses and neglecting my other plants – I have permanently removed the varieties that seem to be prone to black spot. I also will be sure to plant any newly acquired disease resistant varieties in a sunny location that also has good air circulation. My goal is to reduce the potential for black spot to develop on the roses in my garden”
- Cindy Vadakin
-The Petal - June 2008
“I have a case of black spot in my garden at the present time. I am spraying it with Manzate, which is a powder form of a recommended fungicide. It must be mixed in HOT tap water and stirred until it is dissolved, before adding it to a spray container. The dilution is 1 tablespoon powder to 1 gallon of water. It lasts one week. I take care to spray over, under and around each plant. I have sprayed twice with this. The next spraying will be with Banner Maxx fungicide every three weeks. Check the ad in the American Rose Magazine, as these products can be ordered online from Rosemania.com”
- Pat Horbelt
“The #1 thing to remember about eliminating black spot is practicing sanitation in the rose bed. Pick off the diseased leaves (they will fall off anyway) so they won’t lay on the ground beneath the roses and cause more black spot. Then spray the rose bushes and the ground with Maneb or Mancozeb, and the spraying needs to be done before it gets to 85º degrees. Continue a spray regimen with alternating fungicides until the black spot is under control”
- Norma Kemp
“At present I am alternating between Mancozeb (available at Rosemania.com) and Bayer Disease Control for Roses, Flowers and Shrubs. Mancozeb is a contact product and the Bayer is a systemic. The Bayer product is fungicide only, not to be confused with their 3 in 1 systemic or All in One drench, which both deliver insecticide and fertilizer as well as fungicide. I believe it is important to vary the products used so that the black spot does not develop resistance to the product. Whatever strain of black spot I have (there are many different strains) became resistant to Banner Maxx after I used it exclusively for several years. I also occasionally use Neem Oil, a naturally derived product which will kill fungi and insects by smothering.”
- Betsy Latta
“I don’t spray anymore, I just follow good hygiene around the garden and try to choose resistant varieties.”
- Suja Mathew
“I spray with Mancozeb to treat roses for black spot. It will actually kill the spores. You will need to clean up around the base of the rose and remove as many of the diseased leaves as possible before spraying. Mix the Mancozeb in your sprayer using the directions on the bottle. Use personal protection, such as gloves, long sleeves and facial mask as needed. Spray top and bottom of the leaves, as well as the soil around the plant. Water the plant thoroughly before any spray treatments. You will need to repeat your spray routine once a week until you no longer see evidence of black spots”
- Mary Scheulen
“This may seem pretty drastic to many rose lovers, but I avoid spending all my time on my roses and neglecting my other plants – I have permanently removed the varieties that seem to be prone to black spot. I also will be sure to plant any newly acquired disease resistant varieties in a sunny location that also has good air circulation. My goal is to reduce the potential for black spot to develop on the roses in my garden”
- Cindy Vadakin
-The Petal - June 2008
