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Hi guys,

Well, today I was inspecting again my Pyracantha and I noticed that some leaves had brown spots on the underside part. After a thorough search of possible causes I came up with 3 possibilities that were more likely to be the cause of this phenom.

1- Fireblight (I believe that is the appropriated translation for: "Fuego Bacteriano") (This would be my first educated guess)
2- Rust
3- Phosphate deficiency

Now, as I?m not sure at all I would like a positive confirmation on this diagnosis and once is done, if you can, I?d also like you to point me towards the right direction to eliminate this disease.

Thank you all in advance,

Alain

I don't know... not very familiar with pyracantha and I don't recognize the pattern/color - but as it is on the underside of the leaves, have you checked for scale insects? They are brown and may be hard to spot. Probably that's not it though as they would be on the leaves too.

Not sure. Could be some form of fungus infection; What does the top of the leaves look like? Normal?

Auk wrote: have you checked for scale insects? They are brown and may be hard to spot.

Thanks Auk, but I?ve checked that already. You are right they would have been lurking around and at least for the moment its not the case.

leatherback wrote: Could be some form of fungus infection; What does the top of the leaves look like? Normal?

Thanks LB... On those older stablished leaves that are affected they don?t exhibit anything on the upperside, however on young leaves, this phenom manifests itself on both sides...

What could it be then? :blink:

Alain

I have no idea. Could be a response to the weather? But could be a disease.
I would monitor for a few weeks, and if it does not get worse, just wait for winter. Else, trim off infected growth, and treat against fungus (Which I think may be causing this).
But I do not know what it is.

Yes, will do the monitoring. Yesterday I already eliminated the "infected" growth.

Also, today a member of my club told me that Pyracanthas tend to be quite sensible to foliar fertilizers or fluids sprayed onto their leaves. Having done that and also having sprayed soapy water onto the leaves due to an earlier aphid infestation, I find now myself in a greater doubt, since I can?t differentiate between a normal response to these external agents or a fungal disease (as you said) or even some kind of nutrients deficiency...

I can only now keep my regular cares and hope that this might go away... If I had the cause I might attack it properly... I suppose I?ll keep digging for info... As usual, all of your help is well appreciated.

Alain

It is not phosphate. Looks like rust to me, I would not be too worried about it as the leaves will be dropping soon.

m5eaygeoff wrote: I would not be too worried about it as the leaves will be dropping soon.

Firethorn however can keep its leaves throughout winter, if it is not too cold.

But indeed. Just monitor. Trees have a much slower response rate than animals; You can over-nurture plants.

Yes, of course they can keep leaves, mine tend not to, don't know why.

leatherback wrote: Firethorn however can keep its leaves throughout winter, if it is not too cold.

m5eaygeoff wrote: Yes, of course they can keep leaves, mine tend not to, don't know why.

Well, mine last winter kept its leaves alright. Of course, temperature last winter in Ciudad Real never fell below -7 C.

Alain