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Botrytis blight, petal blight, flower blight et al
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Posted by valentine z8 Dallas TX (My Page) on Tue, May 31, 05 at 18:36
| I am organic gardener, and this year, for the first time ever, I have a severe problem that seems to be botrytis blight. At first I thought I had powdery mildew, which is unwelcome, but not disastrous. I had been treating my bush roses organically and I thought I was gaining ground, when seemingly overnight, hundreds of buds and barely opened flowers on my glorious New Dawns turned brown. I consulted Field Roebuck's "Foolproof Guide to Growing Roses" and saw pictures of botrytis blight that look like what I have.
Have any of you organic gardeners had this problem? If so, what did you do? It's going to take me awhile to trim all the affected blossoms and canes, but that is my next step.
An odd thing that happened earlier this spring, that may or may not be related is that on a different, baby New Dawn, several of the blossoms had dark pink stripes on them. I didn't know what to make of it, but I have read that stripes on roses are caused by a virus--which one, I don't know. This rose is in our alley, right across from our neighbor's vegetable garden. It was very curious. Hopefully some of you have wisdom to share. I'll take all I can get.
Thanks,
K in East Dallas |
Follow-Up Postings:
RE: Botrytis blight, petal blight, flower blight et al
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| Have you checked for thrips? Lots of tiny, barely visible, elongated tan insects that scurry to hide when you separate the petals. Thrips damage and Botrytis damage can be confused with each other, or can overlap. Copper soap sprayed on the buds during cool, drippy weather can control Botrytis fairly well, but it may spot some flowers. It is also moderately hazardous, so cover up and then change your clothes if you use it. In Texas, Botrytis should be a transient problem. Thrips are transient for me as well. If you have serious recurring problems with either, perhaps the best course is to discard the most susceptible varieties. If the striped roses are together on one shoot, it could possibly be a valuable mutation, so preserve that wood and see if it keeps producing those blooms. |
RE: Botrytis blight, petal blight, flower blight et al
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| Oh, Michael, would that botrytis were only transient here! Botrytis can be prevented (the best cure) by spraying early in the year, immediately after pruning, with lime-sulfur or Bordeax mixture. Otherwise, during the season, cut out the offending parts. |
RE: Botrytis blight, petal blight, flower blight et al
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| I meant transient in the course of the season, in that it isn't active in hot, dry weather. But it will be around next year. As Field implies, it can affect bark and stems in winter or early spring and cause cane losses. |
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