On 13/09/16 15:52, David E. Ross wrote:
On 9/13/2016 6:56 AM, Mila2015 wrote:
Hello,
I need your wisdom and advise. We live in London and have a mature
Cherry Laurel hedge in front of our house, currently at 8ft tall. For
the past year or two it is unfortunately suffering badly from powdery
mildew and shothole .
We haven't done much about it as we read there isn't much you can do to
cure it. We don't have a gardener and we usually trim the hedge once a
year in late spring when the new leafs become too much. Unfortunately
this leaves us with the old, damaged leafs for the summer.
A gardening company is doing some work currently in houses near us and
they noticed our sick hedge and offered to hard trim it, removing the
damaged leafs ( most of them now ). My question is this: is now a good
time for hard trimming of Cherry Laurel hedge? When is the best time to
do it and try to improve the overall health and minimize the powdery
mildew effect and the shothole?
Any advise will be much appreciated.

Mila

Avoid heavy trimming (see RHS link below). This is important as the
current unseasonal and extremely high temperatures in London will stress
the plant even more.

In the early spring while it is still dormant and out of leaf,

In the UK, cherry laurel (Prunus laurocerasus) is evergreen. Is
something else called "cherry laurel" in the US?

spray it
with a mixture of dormant oil and copper sulfate, with a little liquid
soap in the mix as a wetting agent. Repeat just before the flower buds
open.

No, I do not know if dormant oil or copper sulfate are available in the
UK. In the US, I mix half of what I need of each (e.g., 2 quarts of
each). Then I combine the two batches (e.g., to make a gallon) and add
the soap. I also use this on my roses and grape vines, but I spray them
only once, while they are dormant.

Recommendations for treatment can be found here under "Control":
https://www.rhs.org.uk/advice/profile?pid=568

The only copper product approved for use in the UK is copper oxychloride
(as Bayer Fruit & Vegetable Disease Control), and that is only for use
on food crops. Use one of the "conazoles" or myclobutanil as recommended
instead.

--

Jeff