Re: Powdery Mildew
- To: perennials@mallorn.com
- Subject: Re: Powdery Mildew
- From: L*@aol.com
- Date: Tue, 8 Jun 1999 13:38:02 EDT
David --
That was quite an extensive and good list of powdery mildew remedies you sent.
Kemberly already sent a copy of my previous post on the subject. I have
found those recipes to be quite effective, especially the one with soap.
In addition, there are commercially available, ready-to-use copper- and
sulfur-based fungicidal sprays made by Safer and Concern that are
environmentally safe and effective.
The problem with the commercial and homemade sprays is that they need to be
applied every two weeks through the season, plus after each rain. It can
really be difficult to stay ahead of powdery mildew on plants that are prone
to it -- such as monarda and phlox. If the p. mildew gets really bad, I cut
my phlox back to the ground and I pull the monarda out. The plants always
come back the next spring.
In a good year, I can get a nice blooming period before I have to yank the
plants again. Spraying helps to prolong that bloom time, but I have not
found anything to be totally effective in the heat and humidity of July and
August in St. Louis.
Powdery mildew needs heat and humidity to develop so overhead watering,
especially late in the day is not recommended for mildew-prone plants because
it creates the humid environment in which mildew thrives. Therefore I can
not recommend your remedy #3 -- "strong spraying with water", which could
actually make the problem worse. I wouldn't, but if anyone wants to try
that, it would be best to do it early in the day so the plants can dry out in
the sun.
--Janis
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