Subject: Re: New gardener needs rose help From: "Bill Robinson" <roseguy@gte.net> Organization: Date: Thu, 29 Jun 00 14:44:28 Message-ID: <MOD$000629.5414@rec.gardens.ecosystems>
JTill posted, "If these "new" roses, that is bred in the
last 30 years, then you will have a tough go without
chemicals to control black spot."
I agree that most of the newer introductions are much more
prone to black spot than many of the older varieties and I
also agree that increasing the air circulation around roses
does help in the prevention of black spot. I would just add
that black spot can be prevented a whole lot easier than it
can be controlled. The most effective prevention method is
to select roses that are black spot resistant.
I understand that there has been some work at Texas A & M
that has linked black spot with the genetic make-up of roses.
They are working to breed a rose that will be essentially
immune to black spot and I've heard that they have had some
luck.
See http://victorian-rose.org/Pests/BlackSpot.htm
There is also a commercial CD put out by the University of
California, titled "The UC Guide to Solving Garden and
Landscape Problems", that talks about black spot and its
control. It's available at 1-800-994-8849. I personally
think the CD is terrific but it also cost about $40.