Rose leaf problem -- do you know what this is?

I posted a photo of the problem I'm having with some of my rose bushes at
http://photofan.multiply.com/photos/photo/13/1.jpg
It's going to be a couple of days before I can get a sample over to my local nursery so I thought I'd ask here first.
Does anyone know what the problem might be? Do I need to treat it with something?
The other day I noticed some tiny white specs on some of the leaves and buds. I had a rose insecticide spray handy that I'd had for quite some time, so I shook it up and used it to spray the bushes. Could old insecticide have caused this? Could spraying in too hot Florida weather have caused this?
I spray regularly with fungicide and it doesn't look like black spot.
Thanks in advance for your help
Renee
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Probably powdery mildew, from my superficial glance at it. It's a common problem with roses, particularly in the spring and fall when night temperatures are low and humidity is fairly high. Some varieties are more susceptible than others. It rarely kills the rose bush. Sometimes they will lose the affected leaves and grow others. In any case, with the arrival of summer and warmer nights, the problem should disappear.

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Spray burn. It's probably from the old insecticide. Any sprays that you use should be freshly mixed, and mix only the amount you can use in one spraying. Roses should be well watered before spraying, and you should spray only in the early morning hours when it's as cool as it's going to be. Sprays that use oil derivatives (some insecticides and some fungicides) should not be sprayed when temps are going to be above 86.
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Thanks everyone for your replies. I should have retaken the photo in daylight because the white stuff you saw on the leaf, Presley, was actually the reflection from my camera flash. I feel silly for having missed that! It was actually the brown spot that I was concerned about.
I made it to the nursery and someone looked at some samples, and though she didn't say definitively, she thought it might be burn like you did, Sunflower. I did not spray in the early morning as you suggest. Also, she told me that watering roses in the heat of the day could stress them, too. I wasn't aware of that -- if it's true(?).
I picked up some fresh spray -- Triple Action plus RTU by Fertilome -- an insecticide, miticide, and fungicide in one. It's premixed in a spray bottle. I like being able to just pull it out the cabinet in the morning and be ready to go with no fuss. I plan on using that only periodically when I see insects, and alternating that with my weekly copper fungicide spraying if it's necessary to use it. It's still early and cool enough right now so I'm on my way out to try the new spray and will closely watch how my roses react to it in the coming days.
Thanks again.
Renee
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Copper sprays often burn roses and are not really recommended beyond a narrow temperature range. Fungicides, to be effective, must be applied as a *preventative* on a regular schedule. That schedule is printed on the bottle, as is the diltution rate. Using an all in one is overkill and ineffective. I've yet to see any all in one that does any of the components at all well. If you keep using the regimen you've outlines, you're going to fry all of your foliage and end up with a huge spider mite infestation.

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The nurseries and horticulturists in my area of Florida recommend weekly copper fungicide spraying on all roses except the carefree and low-maintenance ones. Blackspot quickly gets out of control here because of the rain and humidity. I spray regularly with copper fungicide usually in the morning or early evening when the air is still, as recommended by the bottle's directions. So far I haven't noticed any burn problems after using the fungicide.
I plan on stopping my weekly fungicide spray whenever I use the all-in-one. I don't see how that is overkill since the two sprays are not applied during the same week. The all-in-one spray bottle says it's a miticide -- isn't that for spider mites? So I'm surprised you mention that I'll wind up with a huge spider mite infestation if I use it.
I'd like to here your suggestions as to what and why a different regiment would be better. Thanks in advance.
Renee
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here = hear
my English is slipping these days
:-)
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