Help identify and treat this disease on rose bushes?

3 years ago

last modified: 3 years ago

Is this black spot, or maybe some other disease? What would you suggest using to treat it? Diseased leaves are already falling off the bushes. Thanks very much for any help.

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Comments (4)

Moses, Pittsburgh, W. PA., zone 5/6, USA
3 years ago
last modified: 3 years ago
Black spot = fuzzy edged very black spots, some big, some little, adjacent spots grow into each other making a 'mega black spot,' leaves then yellow, and shortly fall off.

Cercospora = even edged black spots with light colored, grayish to light tan centers, behaves pretty much like black spot, leaves turn yellow, then fall off.

You have both. Get it under control with the Bayer fungicide for roses, in the blue bottle. Spray every 10 days, at 1.5 T/gallon of water, for three consecutive sprays, then every 2 weeks thereafter.

Some years are far worse than others for fungus breakouts. To avoid having to deal with black spots and cercospora grow disease proof/highly resistant roses. Ditch the fungus prone varieties, or resign yourself to the fact that they must be sprayed regularly.

Start with these varieties:

Dee-Lish

Quietness

Wedding Bells

Bliss

South Africa

Poseidon

Moonlight Romantica

Earth Angel

FIji

There are others....not many in the big bloomed, showy HT types, although a rose bed dedicated to the above recommendations would be a breeze to care for, and drop dead beautiful.

Moses
Rick (zone 6b, MA) thanked Moses, Pittsburgh, W. PA., zone 5/6, USA
Rick (zone 6b, MA)
Original Author
3 years ago
last modified: 3 years ago
Many thanks for this; much appreciated. I guess it’s pretty common to have both Black Spot and Cercospora leaf spot on the same plant.

I see Bayer is no longer manufacturing these garden products under its own name; I think they spun off their gardening division and that got bought by a French company which uses the brand name BioAdvanced. They don’t seem to make a product specifically for roses but have products like All-in-One Rose and Flower Care, etc.

Thanks again.
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Moses, Pittsburgh, W. PA., zone 5/6, USA
3 years ago
last modified: 3 years ago
Bayer Bioadvanced Disease Control for Roses, Flowers, and Shrubs 32 oz., $15.97 on Amazon. Apply it properly and use it consistently, and it will work. It's that easy.

Moses
Rick (zone 6b, MA) thanked Moses, Pittsburgh, W. PA., zone 5/6, USA
rifis (zone 6b-7a NJ)
3 years ago
If you go the antifungal route, don’t forget rotation to minimize resistance.

I have some roses that are good on blackspot but get a bit of cercospora ( tolerating it w/little ill effect). Examples: Cream Veranda and Pink Flower carpet. I don’t see cercospora on others that are more prone to black spot.

Like “there’s no zoo in zoology”, there’s no Bayer in BioAdvanced ( as you correctly noted, Rick).

If your roses are just beginning to suffer from black spot now, Sept. 13, in MA, that’s pretty good.