KnockOut Rose dying- black spot?

[Izzie]

In my quest for finding some roses that will happily overwinter in CO, I'm trying my first root-rose (as opposed to grafted). (next experiment is a David Austen)
The Knock Out family of roses has had great success in CO.

I purchased it's original member from a reputable local grower: Rosa 'Radrazz' The Knock Out® Rose from Conard Pyle
In true "Izzie" fashion, I spent nearly 20 min looking at each one available until I found one that I deemed healthiest and worthy.

But it immediately started pouting and looking diseased after we potted it.


Took it out of it's original black bucket and potted into a large insulated plastic pot that doesn't get super hot in the sun- it's about 20"x17".

Soil: 1:1 ECO compost: Moisture Control Soil by Miracle Grow

We've never had problems with this mix.


I don't have pictures yet, I'll take some as soon as it stops raining.

It looks very similar to Black Spot. The bush is being defoliated pretty quickly. I have not been able to find any pests.


I've treated with a systemic Ortho rose disease product, with no effect after a week.

Any tips on how to attack this? I've never had to deal with black spot before- just been lucky.

Will Neem Oil put a dent in it?

Should I do antifungal sprays or steer towards antifungal systemics?

It would be a shame to lose this sweet plant so soon.

[camille1585]

Hopefully you'll be able to take some photos soon. I'm not sure about it being black spot based on your description, because it doesn't set in that quickly. Sounds like something else that's quite nasty. But can't say anything until it stops raining and you get pics! And Knock Outs are supposed to be quite disease resistant, so it's strange.

[Izzie]

Originally Posted by camille1585

And Knock Outs are supposed to be quite disease resistant, so it's strange.

Exactly, that's why I'm so concerned. I'll be getting pictures up ASAP.

[johnblagg]

I would use the bayer 3 in one systemic on it ...resistant or not even the fungus's mutate ....probably not black spot but who knows resistant is not immune just tougher.

I have one of the new carefree line from the same guy bred from knock out stock in part and it is supposed to be resistant also an as soon as I potted it up got a lot of nasty stuff on it too .I sprayed with bayer 3 in one and its come right back but still has some deformed buds.And I put mine into miracle grow garden soil ....Had never used that one before and not sure but what the fertilizer was not just a little strong in it.I watered it well over several days to kind of dilute it if possible also.

[Izzie]

We've never had problems with this soil before- we swear by that Moisture Control soil. It works so well in our conditions in CO.

I'll be uploading pictures soon.


We've been putting coffee grounds in all the pots- would that do anything bad?

[camille1585]

Coffee grounds wouldn't do anything bad, they're a good 'fertilizer'. I know it's better to wait for the pics, but if it's not black spot I'm thinking it might be downy mildew (Peronospora sparsa) instead. The symptoms are similar (but spots look a bit different and are more purplish, so if you can get a close up of an infected leaf that would be good) and affected leaves will fall off within days. Black spot can cause severe defoliation, but it takes all season for that to happen, not a week! Have you been having a lot of wet, cloudy icky weather since getting the plant?

[Izzie]

That's a thought...

On the contrary, we've been VERY dry and hot. High 90s yesterday, mostly 80s and high seventies since we got it.

[Eyebabe]

Maybe the place you purchased the rose bush from can identify what the problem might be...?
At the very least, they can maybe replace the plant and give some tips about how to prevent the problem from reoccurring.
"Knock-Out" type roses own-root or grafted are supposed to be one of the most disease resistant varieties available. I know that fact isn't "helpful" but whatever is killing it must be pretty darn nasty

[Gin]

I have several of the Knock Outs they are in the ground not had any of the leaf problems others have and does not winter kill it does get cold here has gone to 0 . I would suspect a root problem ? just a guess .PS# they will grow and bloom semi shaded don't need full sun ..

[Lagoon]

Agreed, Very strong rose bush, very nice choice Izzie
Sounds like it more of a state of shock. Photos will help us alot. Did you do a soil test? I'm wondering if the mix got to acidity.
Something that I have used over the years with great success with black spot, or any fungus related problems is simply dish soap and baking soda.

1 teaspoon of each into a 40 oz bottle and spray down til soaking wet. This is excellent for bugs - ants hate this stuff. UNlike many oils, this mix can be used in hot and humid weather.

Waiting on those photos ......