Thread: Rose disease
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Old 13-07-2003, 11:12 PM
Cass
 
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Default Rose disease

In article MGgQa.52482$N7.6576@sccrnsc03, Ed
wrote:

In May, I planted a #1 "Eden" Climber rose. (Seattle area) June was
unusually hot for the NW, and less rainfall than usual. Rose has been kept
moist and regular fungicide sprays. At planting time, I used Osmocote
18-6-12, and after blooming began, I used Osmocote 14-14-14. (only one
application of each). The bush gets about 6 hours sunlight daily. Daily
highs in the 70's to low 80's and nightly lows in mid 50's.
My problem is this: At first, buds and blooms were prolific. Then, buds
started turning brown before they opened. The bud pedals eventually drop
off the bush after turning brown (without ever fully opening). Right now,
there are lots of buds, all of which are brown and beginning to loose
pedals.
Any suggestions would be appreciated
Ed


Botrytis.
This is what a mild infection looks like after the blooms open:
http://home.earthlink.net/~cbernstei...s/botrytis.jpg
A serious infection looks like this:
http://www.rosefog.us/hipbadprickles...hGardenBad.JPG
And the buds when infected look like this:
http://home.earthlink.net/~cbernstei...trytisbuds.jpg

Do a google search of botrytis rose. My Eden Climber, aka Pierre de
Ronsard, loses the spring flush every year to botrytis. The blooms make
a big mass of petals and must be cleaned up religiously. Don't let them
age to the point of getting polka dots or brown edges, much less fall
off and lie on the ground. I'm sorry to say that apart from climate
change, I know of no solution for botrytis other than spraying
fungicide or removing the plant. Extremely healthy roses that produce a
mass of flowers are susceptible under the right climatic conditions:
cool and damp.

You can start a very disciplined systematic spray program and rid your
garden of this blight now. Then you can try to be on the lookout for
botrytis in the future and clean up all the failed buds and spent
blooms before they show the polka dots of botrytis. I'm afraid that in
certain climates, the fungus is widespread in the environment and that
roses with buds that sit on the plant for a long time can be infected
from outside the rose garden. This is my opinion only, derived from
finding botrytis in my garden on roses that are a long distance (50
feet) from other roses with botrytis during an atypically cool, damp
spring.

There is a single, most effective fungicide for botrytis, available by
mail order at great expense. It may not be approved for use in
Washington.