Can anyone help with leaf problem??

astronomer2(6)May 4, 2014

2-3 weeks ago my rose plants all looked fresh and green, really nice. Now I'm seeing leaves turning brown and dying. See image. I use only Rose Tone and alfalfa pellets, no chemicals.

We did have several nights 7-12 days ago that got down to 38 degrees, and I didn't see a heavy frost but maybe there was a little. Could that have done this? I see this on at least one third of my roses. Many thanks, David

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jacqueline9CA

It could be burn from the cold, if the foliage was very tender. What is the white stuff on the leaves?

Jackie

    Bookmark   May 4, 2014 at 3:38PM
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henryinct

It is certainly severe stress but it wasn't cold enough to do such damage. Look at the canes. Back in CT I used to get canker this time of year. The easiest thing you can do is check the moisture to see if they are too wet or too dry. They should be moist. I would cut back that cane in the center to healthy white pith and look to see if you are getting basals. You should be. If not and the rose appears to be slowly dying then it must be a root problem. When it got to be so it looked terminal I used to cut them back, dig them up and inspect the root system and often find a problem and then pot them and hope for the best. Good luck.

    Bookmark   May 4, 2014 at 3:54PM
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astronomer2(6)

thanks to you both... the white on the leaves is spray for fungus, Daconil. What do other folks use for black spot etc.? I wouldn't expect a root problem on so many. I'm seeing this on one-fourth to one-third of my roses. David

    Bookmark   May 4, 2014 at 4:53PM
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henryinct

Daconil is a chemical that can cause what you are seeing.

    Bookmark   May 4, 2014 at 10:06PM
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greentiger87

How familiar are you with Daconil / have you used it on roses before? It's notorious for causing phytotoxicity, susceptibility varies by variety.

General consensus is that the best conventional "spray" for blackspot is tebuconazole, sold as Bayer Advanced Disease Control.

Bayer 3-in-1 has it as well, but at a lower concentration and also includes the controversial insecticide imidacloprid. I won't go into it here, as it's been discussed to death on the boards... but don't recommend it personally.

You should rotate with a fungicide from a different class. Mancozeb is the most commonly available for the general public, sold under a variety of names. It's much less phytotoxic than chlorothalonil (Daconil) - but you still need to make sure your roses are well-watered and that leaf temperature is cool and won't rise dramatically until it dries - early morning is ideal. Night works too, if you don't mind spraying in the dark - but make sure you wait until the leaves have cooled down after sunset.

    Bookmark   May 4, 2014 at 10:23PM
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mzstitch(Zone 7b South Carolina)

It could be your rose was dry when you sprayed the Daconil. Personally I tried Daconil but it didn't successfully hold off blackspot on my roses. Bayer Advanced Disease control is the only one I use now. For me it's major advantage is it stops blackspot in progress. So if my rose plant begins to get Blackspot I start the spray program and it stops it from spreading. It also will not leave the ugly white film on your plant as well, it dries clear. Make sure your plant is well watered before you spray, I usually water my roses the day before I spray. I still think it looks like frost damage, as some of mine have the same damage especially since it looks like the inner leaves are fine and the outer leaves show the damage. It should recover fine and releaf.

    Bookmark   May 4, 2014 at 11:05PM
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astronomer2(6)

I really appreciate the thoughtful replies. I should have mentioned that the leaf problem showed up well before I sprayed the first time with Daconil, so don't guess I can blame that. But I have been very unhappy with the white residue. I will buy Bayer Advance Disease spray today.

I guess the cold snap is the most likely culprit. Should I be using fertilizer besides Rose Tone and alfalfa pellets?? Someone advised me to use Miracle Grow for Roses every two weeks, but I have not done that. This is a very useful forum! David

    Bookmark   May 5, 2014 at 7:14AM
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dublinbay z6 (KS)

Rose Tone and alfalfa pellets are sufficient. Nothing else is needed. In fact, the pellets may not even be needed since Rose Tone already has some alfalfa in it.

What rose is that? If it is Double Delight, you need to know that DD hates Daconil.

Kate

    Bookmark   May 5, 2014 at 7:33AM
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astronomer2(6)

to dublinbay: I'm convinced my problem was frost. My roses are now looking pretty good for this time of the year. The rose shown is not Double Delight. The name I have down for it is Spicy Fragrant, but I'm a little worried that this name is incorrect. I keep a table with all of my roses listed, with name and year acquired, so I don't have any reason to doubt this name, but I can't find anything about it on the internet!! Thanks for your help, David

    Bookmark   May 12, 2014 at 7:17PM
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