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Worrying leaf colour on Rhododendron

Cornish CanaryCornish Canary Posts: 21
in Problem solving

image

I've become a little concerned by a few of the leaves on my Rhododendron which as you can see are looking a little worse for wear. I Iive in Cornwall so don't suffer with any major frosts, I applied a granular fertiliser liberally to my shrubs a couple of weeks ago and wonder if this could be a sign over over fertilising. The shrub is situated in a shelter area of the garden and upto this point has been very healthy.

Would be interested to know what you think it may be and what I should do to remedy.

Thank you in advance!

 

Posts

  • Dave MorganDave Morgan Posts: 3,123

    Worringly that could well be phytophthora. There's no treatment for it. You could try improving the drainage. Pick off the affected leaves and burn, only time will tell. It doesn't appear to be anything that classically affects rhododendrons.

  • Cornish CanaryCornish Canary Posts: 21
    Dave,



    Thank you for getting back to me, I will google the disease you mention, although it sounds very ominous. Would be gutted to lose this one, it was a former Chelsea flower show shrub which I paid good money for! Drainage is very good in the area. Would you definelty get rid of the affected leaves regardless of the issue?
  • Dave MorganDave Morgan Posts: 3,123

    It's all you can do Cornish. It may well die but be optimistic.

  • Cornish CanaryCornish Canary Posts: 21
    OMG, just research phytophthora, couldn't be much worse if that is indeed the problem. I have an expensive acer and several azaleas nearby. Should I allow it to flower and then take further action? I have removed around 8 leaves, there are others with much milder symptoms which I have left at the moment.
  • Dave MorganDave Morgan Posts: 3,123

    Are the symptoms similar on the other leaves Cornish?

  • Cornish CanaryCornish Canary Posts: 21
    It hasn't affected all of the leaves. I have removed around 8 which have similar symptoms to the picture above. There are around 5-10 more on the whole shrub which have far less dark patches. I think this is just wishful thinking but I take it frost and/or over fertilising wouldn't be the cause?
  • Dave MorganDave Morgan Posts: 3,123

    Frost and fertiliser wouldn't cause that no. Let's live in hope shall we.

  • Cornish CanaryCornish Canary Posts: 21

    Thanks Dave, appreciate the advice. Fingers crossed it will be OK! It's a big shrub (around 1 meter x 1 meter) so that gives an idea of the percentage of leaves affected which is relatively low. Thank you again.

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