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Blooms with Brown Edges

Posted by jbfoodie z10 CA (My Page) on
Tue, Jul 29, 08 at 11:44

I have noticed this year more than any other that my white and light yellow roses tend to get some brown edges on the outer petals during the summer months. Before the blooms even open, I can see browning on the flower. Does anyone know why this happens? Could the soil be too wet? Too dry? Is something missing in the soil? Does anyone else have this problem? I do not spray and I have heavy clay soil, so drainage is not perfect. The temps have been in the 80's most of the time this summer, with a few higher and lower days.

Any help will be much appreciated.


Follow-Up Postings:

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RE: Blooms with Brown Edges

Joanne, Mine are doing the same thing. Prairie Star, a white Buck barely opened and some are brown buds. I wonder if it's a combo of something. I'm thinking of the people who grow Buck's in TX and their heat, and what theirs are doing.

Carla


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RE: Blooms with Brown Edges

Carla--the offenders in my garden are primarily Etoile de Lyon, Souvenir de Pierre Notting and Coquette des Blanches, though there are a few others that exhibit some of this behavior. The leaves and general health on these three roses is superb, which makes me think it is not a drainage problem. Maybe it is just a reaction to the high temperatures?


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RE: Blooms with Brown Edges

Have you checked for thrips by shaking a bloom over a piece of plain white paper? I have the same problem with light flowers in the middle of summer, prime thrips season in my garden.


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RE: Blooms with Brown Edges

What do thrips look like? I have not noticed any bugs, but I will try the 'shaking a bloom over a piece of plain white paper' suggestion to see what happens. Thanks Berndoodle.


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RE: Blooms with Brown Edges

Actually most of my blooms look like small globs of mushy toast.

Carla


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RE: Blooms with Brown Edges

Berndoodle--I tried your 'shake the rose' method of insect determination and found that there were in fact about 2 or 3 brown slithery bugs about 1 mm long. Without a magnifying glass I could not see any details, but they crawled in a very snake-like fashion across the paper towel. They did not fly off the towel, however. Are these thrips?


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RE: Blooms with Brown Edges

  • Posted by hoovb z9 Southern CA (My Page) on
    Tue, Jul 29, 08 at 20:29

Sounds like it. Not only are they a bane to roses, they can also invade LCD monitors.

There are several thousand different species of Thrips.

Here is a link that might be useful: Thrips in LCD monitors


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Another shocking Thrips fact

'Some plant-feeding thrips are also predaceous on other pests, such as spider mites. In young cotton seedlings in California, western flower thrips is considered beneficial because it feeds on spider mites.'

Here is a link that might be useful: Thrips info at UC Davis


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RE: Blooms with Brown Edges

jbfoodie, in the larger scheme, 2 or 3 thrips isn't anything. Try again at a different time of day and look for an open bloom with many petals and a light color. Then choose a dark red or deep pink bloom and do the same thing. At times I can see a dozen or more thrips on the paper. The interesting thing is that the dark blooms will have just as many thrips but show little damage. It's something in the pigment. The two signs of heavy thrips is balling in the middle of conditions where there hasn't been rain or other heavy humidity to blame and light blooms showing the effect of dark brown on the petals' edge, as if burned with a blow torch.

In my gardens, I see no thrips damage until late June. It lasts through August or so. The mid-September through October flushes are again fine. My gardens both adjoin large areas of dry grasslands that dry out by mid-June. My impression is that those meadows act as thrips breeding grounds and that once the summer foggy winds start blowing the thrips are blown into my gardens. I once tried - - exactly one time - - to spray for thrips. Hah! What a fool's errand. Between the wind, the 5 day spray cycle, and the suggested spray application on the buds only, I realized I didn't want to be that deeply involved in the day to day interactions between my roses and their bugs.

My garden areas with a sizeable irrigated garden buffer between the roses and the grasses are much less troubled by thrips. Or maybe it's the direction of the wind - the roses on the western edge screen out all the thrips, and by the eastern edge, there are very few. They are a pain, but much a less a pain with many deep pink or red roses, that can be crawling with thrips, still open and show only minimal scorching on the petal edges.


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RE: Blooms with Brown Edges

Berndoodle--I have noticed some balling in the hot summer months here. The buds are brown on the outside. It does seem to start around June. I am in a suburb surrounded by dry hills. Perhaps this is how they are making it to my garden. It is little enough damage really. The deer are far more destructive on the roses in my front yard than the few summertime thrips. I will just put up with it as I am not about to start spraying. I will check out the pinks and reds as you suggest. Thanks.


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RE: Blooms with Brown Edges

That's pretty interesting, Berndoodle. I've always wondered how thrips can be selective about color when I think they get into the buds before they open and show any color. I've seen thrips on dark roses too...I think you're right that the dark ones just don't show damage as much.

I'm getting balled blooms and brown edged ones too.


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RE: Blooms with Brown Edges

hoovb--it may be that these are the 'Western Flower Thrips.' The coloring sounds like the description at the website you posted. I do have spider mites, so maybe these will be somewhat helpful.

I noticed this morning that zillions of thrips were crawling all over my Kronprincessin Viktoria, but for some reason these blooms show very little damage. The insides of the blooms were definitely beginning to brown, but the rest of the petals looked just fine. At least now I know why my roses look this way.


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