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13 messages
25/06/2014 at 17:10

We have a stand of very tall, mature Rhododendron ponticum in our garden, one of which has developed a lot of very dark brown, almost black spots on the leaves. The edges of the spots are flared with purple, and then yellow.    The spots are visible on both sides of the leaves.  I will try and post a photo, unless someone knows what this is?  Many thanks 

25/06/2014 at 17:43

OK! hopefully here is a photo!

http://s4.gardenersworld.com/uploads/images/original/50757.jpg?width=250&height=350&mode=max

 

25/06/2014 at 19:04

http://www.countrysideinfo.co.uk/rhododen.htm

Sorry, not my cup of tea at all. 

26/06/2014 at 08:03

It is not something I would have chosen to plant, but they have been there for thirty years or more.   I was more concerned that it as not harbouring some disease that will ultimately affect other trees and shrubs growing in the area.

26/06/2014 at 08:30

Hi Linda

Black spots with a purpley tinge is a fungal infection but wont kill it, you could spray with fungicide but there is no guarantee that it will be effective and it wont be pratical to spray on a tree of that size

Its also unclear if this fungal infection will spread to other plants, maybe somebody else on the forum has a better idea

The biggest problem is the plant itself it will outcompete everything all around it

26/06/2014 at 09:21

I know!   I am forever pruning them to stop it taking over. Trouble is, on the Isle of Man you need permission to fell any tree over about 6" diameter.   They do look beautiful when they are in full bloom, but the rest of the time they are rather boring!

26/06/2014 at 09:30

Hi Linda

Does the garden police know its there not that Iam implying anything

Maybe you could be over exuberant with your pruning

26/06/2014 at 11:47

Is rhododendron a tree?  I imagined it was a shrub that could sometimes grow to tree proportions.  Could be your get out clause

26/06/2014 at 15:23

The stand of rhoddies is in a very prominant position.  I think someone would notice if they disappeared!   Shrub/tree it makes no difference.  Besides I am not really sure I want to remove them, only to be certain that they haven't got something which would spread.... then they would have to come down.

26/06/2014 at 19:00

 

 

01/07/2014 at 07:30

I will take further photos, as there appears to be two sorts of problem leaves.  The ones I have already shown you and other ones which are much more severe, with the leaf browning from the tip.Will go get the camera folks!  Am buping this aas I have a problem with a Quickthorn which appears to have died in a week!

01/07/2014 at 07:56

http://s4.gardenersworld.com/uploads/images/original/51200.jpg?width=250&height=350&mode=max

 

01/07/2014 at 14:58

Linda, try googling Phytophthora cinnamomi + Rhododendron as well as Phytopthora ramorum + Quickthorn and have a look at the pictures coming up. If your plants look like that, I'm afraid you might have a problem. 

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