Rhododendron hep

darrencnel · June 2023

Hi all,

i have a few lovely longstanding Rhodies that have been in a bed for many years. a number of years ago the leaves started turning brown/black and a number of the flower heads would die before flowering. The new growth that would come after flowering would, however, look very healthy and green and without any signs of apparent disease. BUT.... by the time we go through winter and spring approaches the leaves are in a terrible state once again and it seems like more and more of the (leaves and Buds) are being affected year on year. I was wondering if there is any advice to be had. I have never pruned them back or treated them with fungicide, would this make a difference?

thanks in advance

Image: https://us.v-cdn.net/6030279/uploads/editor/n1/y6kqhmns5c3r.jpg

bédé · June 2023

It might be Phytothora ??? I hope not.

Lyn · June 2023

Looking at photos 2 and 4 is it in that narrow container, they like to spread their roots out horizontally but shallow.

darrencnel · June 2023

@Lyn it looks like a horizontal container but we have a decking and the soil goes under it somewhat so it is not as narrow as it looks.

Fairygirl · June 2023

Can we have a wider view of the shrubs @darrencnel ? Unless they're getting enough water, and the soil's in good condition, they could be struggling generally, which leads to other problems.

Flowerheads dying before opening properly suggests dry soil, which means the buds and flowers are stalled in order to save the main plant, and if they aren't getting adequate moisture in late summer, that's also a problem as that's when the buds form.
Leaves becoming black can also be a sign of sooty mould, and that can be down to poor airflow causing stress, and then various sap sucking insects getting a hold.
You can prune them if they're not in an ideal site too, but it's hard to see exactly how they're being grown from the photos.

Rhododendron hep

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