Re: Red blotches on hawthorn leaves
- To: m*@ucdavis.edu
- Subject: Re: Red blotches on hawthorn leaves
- From: D* M* <i*@cgac.es>
- Date: Sat, 01 May 1999 09:10:03 +0200
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 Martin
Talavera, Spain
Jerry Heverly wrote:
> I admit I passed over your message owing to the fact that plant diseases
> are generally localized and I despaired of identifying any pathogen 7,000
> miles away....but after further reflection I decided, what the heck, why
> not take a crack at it. So I consulted my reference books for US plant
> pathogens. We have a marvelous reference in this country called Wescott's
> Plant Disease Handbook, which has attempted for decades to provide a
> catalogue of every reported plant disease in the US, listed by state. I
> wondered if one of our organisms might also be about in Spain.j
>
> There really are only two possibilities, both fungal.
> The most unlikely is Septoria leaf spot. There are a zillion Septoria
> organisms in the US affecting just about any plant you can name. Most
> cause roughly circular spotting on leaves and/or fruit. The most common in
> California forms reddish blotches on english ivy(*Hedera helix*). There is
> a septoria reported on Hawthorn but the text doesn't give any description
> and it has been reported only in the extreme north part of the country in
> Michigan, Wisconsin and North Dakota.
>
> A more reasonable choice is *Fabraea thuemenii*, Hawthorn Leaf Blight.
> Wescott describes the symptoms:
> "Small dark brown or reddish brown spots , with raised black dots, are
> numerous over leaves, which drop prematurely in August. In wet seasons
> trees may be naked by late August." We have a related disease,
> *Entomosporium leaf spot* in the San Francisco Bay Area affecting
> ornamental pear(Pyrus kawakamii* and *P.calleryana*), *Photinia fraserii*
> and *Raphiolepis indica*. It has become such a problem that people are
> just beginning to shy away from the latter plant; probably a good thing as
> Raph's are greatly overused.
> Jerry Heverly, Oakland, CA
>
>
>
At 9:43 AM 4/29/99, Damian Martin wrote:
>I planted a few local hawthorns (Crataegus monogyna) last year.After a
>short burst of healthy spring growth, they came out in red blotches,
>specially oin the tender young leaves at the tips of branches. Later, in
>the summer, the blotches spread to older leaves infesting most of the
>plant. The centre of the botch finally turned into a root-like outgrowth
>on the leaf's underside. The result was a set of very sad hawthorns with
>no post-summer growth at all. I treated with fungicide to no avail. I
>cut back in winter but, on inspecting the new shoots yesterday I found
>the same little red spots appearing. Help!
>
>This is probably a well-known disease... but not to me. Any suggestions
>most welcome.
>
>Damian Martin
>Talavera, Spain
