Re: Red blotches on hawthorn leaves
- To: Mediterannean Plants List <m*@ucdavis.edu>
- Subject: Re: Red blotches on hawthorn leaves
- From: T* &* M* R* <t*@xtra.co.nz>
- Date: Sun, 02 May 1999 13:27:56 +1200
- References: <372AA8CB.6794@cgac.es>
Damian Martin wrote:
>
> Jerry, thanks a lot for your time and effort. At least I seem to be on
> the right track by using fungicide. Trouble is I suspect the treatment
> its not specific enough - Also I am making an effort not to bring any
> chemical controls into my wildlife garden so it annoys me to have to use
> the spray. I wonder if with successive cutting back it will just die
> out?
>
Damian
Unless only odd shoots are affected, I fear cutting back is only likely
to mutilate your tree to no good purpose.
As hawthorns are deciduous one must wonder where the fungus spends the
winter. Most likely it survives as spores on fallen leaves and on the
bark. You could cut down the possibility of reinfection a lot by picking
up the fallen leaves and burning them or alternatively covering them
with a thickish mulch (say 5cm).
As to any spores on the bark you could try smothering them over winter
with a simple oil spray.
Even with these precautions, it is still unfortunately likely it may
start again on the new leaves.
Supposing it is Fabrea, there is a related species which attacks Quince
and which I have controlled quite well in my own garden by a protective
spray of compost tea - Compost (10% by volume) soaked in water for three
weeks with ocasional stirring, then strained and sprayed neat over all
surfaces as soon as leaves open, repeated at least three times at
two-three week intervals. This never completely controls the spot, but
markedly reduces it and prevents a lot of premature leaf fall. I suppose
if one was prepared to continue spraying most of the summer for a season
one might have a chance of getting rid of it completely, but as mine was
in residence at least thirtyfive years before I started this particular
treatment it is a bit too established to control easily. As the compost
is solely protective, it is essential to get it on the leaf surfaces as
soon as they are exposed and before any fungus spores present can start
their penetration.
Interestingly, it gives markedly better control than the copper spray
traditionally recommended against this spot.
Moira
--
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata,
New Zealand (astride the "Ring of Fire" in the SW Pacific).
