Petite Rose Mold/Fungus??? Help!

Wyndsong

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These are a picture of the worst from my two little bushes of Petite Roses. They are a special type of rose from this company, and I’m afraid I can’t remember the exact name of the genus (?). Most of the flowers are not this bad, but the majority of the ones that I had to prune off today had some of this white/brownish substance on them.
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In case this matters, here’s some details on the placement of the flowers, etc. We bought them at a local nursery and transplanted them into a big flower pot, one for each of the bushes. They sit on our front porch. We water them around twice a week. Unfortunately where they sit, they do not get a lot of sun. Probably just a couple of hours in the late afternoon. We are aware that they should be 6 or more hours of sunlight, but we were hoping that we could get away with the less hours and maybe not as big or bright of a bloom. The pots that we planted them in were left with the house when we bought it. The plants that were in them had died from lack of water (we weren’t taking care of those plants LOL). We used the soil that was in the pots along with the soil that the plants came in when we transplanted them. Plus we added some super thrive to the soil as well. It’s like a fish emulsion mixture.

Anyway, we’ve seen this substance start appearing and getting more and more. We’ve only had the plants for about 3 weeks, so not that long. Not sure what this stuff is or how to get rid of it if we can. Maybe it’s not a big deal, but it looks pretty gross in person. Can anyone help figure this out? Thanks in advance!
 

Dirtmechanic

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So superthrive is a auxin, basically like a rooting hormone. Auxins are produced in the tips and travel to the roots. They produce cell elongation and fail in the sun which is why the plants bend to the light. A hormone that is similiar but maybe better for fungus is: "Salicylic acid (SA) is an important plant hormone that is best known for mediating host responses upon pathogen infection. Its role in plant defense activation is well established, but its biosynthesis in plants is not fully understood." (wiki).

Cytokinen which is in fruit set spray for tomatos and peppers, helps flowering and lateral growth. It come from the roots up. When you trim the tips off a plant and it grows bushier, you are seeing the effect of its influence in the abscence of auxins formed in those removed tips.

You will need more sun.

I use Clearys 3336 fungicide to stop black spot, and it works on mildews like you are showing as well. Aspirin uses acetosalicylic acid which is close but not quite the same as salicylic acid. It will inhibit powdery mildews. Mixed with water a powder residue will get left until its washed off.

It may just be easiest to use a 3n1 product that has funicide, insecticide and fertilizer combined.
 
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flowerbug

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are you sure it's not a bug? i can't really tell from the picture. fungi can attack just the flowers but it's not that common in my experience.

where abouts are you located?

do the planters have drainage holes? is the soil waterlogged?

anything else you can say about the conditions where you are at the better.

anti-fungals can help, but if the overall conditions aren't good for those plants it's a waste of money to use it - i'd change out the plants for something else that is more shade tolerant. and while i was at it i would also replace the entire contents of the planters.
 
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