Is there any hope for this rose bush?

[Lmbauer2017]

Howdy,

I’ve had this bush for a few years now. The leaves are getting black blotches on them and turning yellow. I sprayed last week with a hydrogen peroxide mixture (6oz/gal) which has helped many of my other plants in the past combat leaf spot. I just sprayed again this morning and it’s definitely worse.

Last year, I let a Texas sage bush near it turn almost completely black with some sort of mold. (I think it came from whiteflies which were plaguing my garden that year) I just didn’t have time to spray it or have the will too (was going through a rough patch in life). This year, I’ve been spraying that sage regularly and I see a significant decrease in the spread of the blackness. I’m not sure if that’s the same blackness as what’s on the rose bush, but I figured that’s relevant info jic.

If anyone has any advice or success stories I’m all ears and would greatly appreciate it <3

And (possibly relevant) here’s the only pic I have from LAST year of the black spots on the Texas sage bush. This thing was completely covered months after this pic was taken:

 

[YumYum]

My experience using hydrogen peroxide as a fungicide is that if it does kill/stop the fungus, the leaves never really recover and you may just be looking at the damage left behind while the fungus may be dead. You really have to hit the fungus as soon as you see the problem.

What strength did you spray the leaves with?

 

[Lmbauer2017]

6oz (3% H2O2) in 1 gallon. I’ve only sprayed it once as that was the first time I saw it. I’ll probably hit it again tomorrow or the day after at least, and keep doing it each week and see what happens. The major concern is it’s spreading to the rose bush near it . So I included that one in the spray today.

 

[YumYum]

I'd go with 1 cup per gallon or even 2 cups. Hit it right after a rain and the leaves have dried. I've never sprayed roses but I have blackberries.

 

[cpp gardener]

You have blackspot on the rose and peroxide will do nothing to control it. You can spray with copper or sulfur to help control it or you can use Funginex if you want to stop it. The sage has aphids and sooty mold is growing on their honeydew droppings. Use whatever control you usually use for aphids.

 

[YumYum]

I noticed the sage had different spotting too.

You have blackspot on the rose and peroxide will do nothing to control it. You can spray with copper or sulfur to help control it or you can use Funginex if you want to stop it. The sage has aphids and sooty mold is growing on their honeydew droppings. Use whatever control you usually use for aphids.

Have you tried hydrogen peroxide on blackspot before?

 

[Tetters]

Blackspot is a real pain, and very difficult to deal with. It is very important to clean away every single bit with the spots on, and rake up all the leaves and burn them. The English are proper rose fanatics, and the rose beds of England are well documented. Even when different roses are supposed to be resistant to this - they still have the problem.
I don't think that the disease can be cured, but by total cleaning it can be slowed down. As well as infected leaves, the affected stems should be burned too, never try composting them, it will just spread the disease. Pruners should be spotlessly clean before pruning these plants, and definitely disinfected again immediately afterwards. Being as cautious as this can prolong the flowering life of the plants. In an extremely bad case, it's best to simply dig the rose out and burn the entire thing.
No amount of sprays will help - that is just a waste of time and money in my humble opinion...... (or maybe not so humble?) ...

 

[DirtMechanic]

Clearys 3336 will knock blackspot back for a year or more once you get it under control. It is a systemic fungicide. The spot gets started in the propagation at the nursuries. They have found that heat can kill it but many plants die during that process so expect more expense to aquire them. And if you do not do as @Tetters says it would come back anyway. A lot of 3-N-1 rose fertilizers have fungicide that is along the same line. Expensive stuff these days.

 

[Lmbauer2017]

Clearys 3336 will knock blackspot back for a year or more once you get it under control. It is a systemic fungicide. The spot gets started in the propagation at the nursuries. They have found that heat can kill it but many plants die during that process so expect more expense to aquire them. And if you do not do as @Tetters says it would come back anyway. A lot of 3-N-1 rose fertilizers have fungicide that is along the same line. Expensive stuff these days.

Awesome I’ll check it out. So I’m actually remembering that this happens in the beginning of the year (or it did last year), and then cleared up somehow or was small enough that I didn’t notice… I was spraying neem on a few plants fairly regularly though so that may have helped. Good to know it’s not related to this poor sage bush spreading its own black mold around. Btw that bush has been looking amazingly better since I’ve been drenching it in peroxide lol. So that’s at least one win!

 

[big rockpile]

Keep in mind if you're trying Organic the Peroxide will kill Microbs.

I to was wondering about Neem.

big rockpile

 

[Tetters]

With a few (naughty) exceptions, I prefer all to be organic, NO exceptions anywhere near food crops though. Working WITH nature is by far the best way. I decided that many years ago, and generally speaking the whole plot has benefited hugely.

 

[Lmbauer2017]

So what happened is exactly as I predicted (which is what happened last year). ALL the leaves died, and the bush has sprouted a flush of new ones. I’ve been spraying neem weekly, but I think it’s a combination of old leaves staying on all winter (I’m in Houston), then temps warming up and black spot activating. Then the leaves die off, and new ones (with no black spot) take hold. Maybe the spraying is keeping the black spot at bay now that the leaves have a fresh start. I’ve found neem to be a fantastic almost-cure-all, especially with nasty stuff that peroxide doesn’t manage. It just requires consistency for a few weeks and then easing off so whatever ailment doesn’t build up a resistance.

About the peroxide, I only use that on my tomatoes and this Esperanza tree both of which get copper leaf spot really bad (it’s prevalent in my garden unfortunately). I have to start them off with minimum 1 spray per week at the start of a wet and HUMID season. Once things warm up, I’ll usually hit them maybe 1-2 times per month. I’m trying to use almost no neem anymore unless a plant is getting completely ravaged (like my peppers right now). I don’t mind a few caterpillars eating leaves and providing food for parasitic wasps etc as my garden has FINALLY begun to balance out and take care of itself.

Thanks again for all the help y’all! I’ll post an update pic when I get a chance.