Black Spot that refuses to go away, HELP!

14 years ago

IÂm hoping someone can help me out. We have a long bed of tree roses that are about 3 years old and have never had any problems other than occasional aphids. They are well cared for and have received regular fertilizer that is supposed to help prevent disease.

They bloomed very early and vigorously this year. Then they (and I mean all of them) developed about every rose problem you can think of: mold, black spot, thripes, and tons of aphids. We treated them with a fungicide/pesticide after removing all damaged leaves and hard pruning them. All leaves, canes, and even the surrounding ground have been sprayed. Weekly we do the same thing (minus pruning): remove damaged leaves and spray.

After 5 weeks of treatment, all problems are gone except for Black Spot. It appears to even be getting worse; now the thorns on some canes are completely yellow and some canes have even turned yellow. We are puzzled. The tree roses are never overhead watered and the temperatures here are in the 90s during the day and high 70s at nightÂweÂre dry heat as well, no humidity. We have none of the causes of Black Spot and yet every week there is more yellow. The new growth appears to be healthy but IÂm concerned about the infested leaves further down on the branch where the new growth is sprouting from.

We are so frustrated and worried these roses wonÂt make it. Any help would be very much appreciated.

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Comments (8)

dublinbay z6 (KS)
14 years ago
What are you spraying with? What you need is a systemic fungicide. I strongly recommend Bayer Advanced Garden Disease Control for Flowers and Roses. (Don't confuse it with the other Bayer products--I do not recommend them.) The Bayer Garden Disease Control can be found a Lowes or ordered online.

If you have a new outbreak of BS, spray this product weekly for a couple weeks. Then back off and spray only every 2-3 weeks. If your weather gets very hot in mid-summer, you may not need to spray then since very hot weather is not conducive to BS.

On the other hand, if your new growth is healthy, don't worry about it.

As to the yellowed canes, I have no idea about that, but overwatering can cause a host of problems. Hopefully someone else can address this problem.

Kate
roomtoblossom
Original Author
14 years ago
Thanks for the speedy reply! We've been using Spectracide Immunox Plus. I will definetly pick up some of the Bayer next time I'm at Lowes and switch to that. The odd thing with the weather is that we've already had a few days of 100+ degrees-- for once I'm hoping for more. I'll have to watch the watering as well. Thank you so much for the advice. Hopefully someone knows something about the yellowed canes/thorns.

-Lauren
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sammy zone 7 Tulsa
14 years ago
Do you know for a fact that it is black spot, and if it is, are you using proper protection if you are spraying trees? Are those chemicals falling on your head?

There is a lot of information here, and also your local consulting rosarians have information. Before trying to find the correct chemical, perhaps you should consider consulting the Consulting Rosarians at your local Rose Society or the Master Gardeners. You may consider switching to roses that do not require spraying. Even if you are pouring the chemicals in the ground, that may not be what you really want, and perhaps you do want it.

I think investigating your options is a good idea.

Do you know the names of your roses?

SAmmy
texaslynn
14 years ago
You might alternate the Bayer with Mancozeb. I have also read (although I haven't done this) that for severe infestations, to spray every three days instead of once a week until it is under control (trying to remember where I read that recommendation). Maybe someone else has a thought about that tight spraying schedule?

Good luck!!!

Lynn
aurora1701e
14 years ago
What Lynn said. Mancozeb sprayed every three days for three intervals. I had a horrible infestation last year and it cleared up after using Mancozeb.
buford
14 years ago
Keep spraying the new growth with the Bayer. The older growth will never improve, so just pull it off if it bothers you.

With fungicides, even the Bayer, that will stop BS, it's always best to spray before the BS shows up.
york_rose
14 years ago
Black spot doesn't grow well in a dry climate. There are many others here more experienced than me, but I can't recall black spot (& my roses get it) ever affecting the canes or prickles. If you're canes & prickles are yellowing I suspect you have some other problem than black spot. Black spot defoliates the canes, but it won't yellow them to the best of my recollection. I don't quite recall for certain, but to the best of my recollection black spot only infects rose leaves, not the rest of the bush's tissues.
olga_6b
14 years ago
BS can infect canes, but usually they don't turn yellow. I agree with York rose, if canes and thorns turn yellow, you probably have some other issues. Pictures would help to find solution to your problem.
Olga

Black Spot that refuses to go away, HELP!

Comments (8)

dublinbay z6 (KS)

roomtoblossom
Original Author

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Black Spot that refuses to go away, HELP!

Comments (8)

dublinbay z6 (KS)

roomtoblossomOriginal Author

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roomtoblossom
Original Author