By Nariz
Spain 
I asked a question about my sick Rhododendron a few days ago and Pimpernel suggested it might be Phytophthera. I Googled this and found it means - in Greek - "plant killer!" So ... after finding that the disease seemed to be spreading to the new shoots which had, until then, seemed perfectly healthy, I decided to dig it up and dispose of it. I was surprised to find that, despite having been planted into the ground in ericaceous compost three years ago, it had made no apparent root growth, even though it had been regularly fed with a good Spanish brand of ericaceous feed and had been regularly watered. Did it perhaps have the disease when it was in the original pot, or when I planted it into a large tub, or when it was planted into the new compost in the ground? The question is now academic as it is an ex-Rhododendron, but I am interested to learn where the disease came from, whether it may still be present in the ex-hole and whether there is anything I should do to ensure that whatever else is planted there in the future does not become an ex-plant!
8 Jul, 2012
Answers
I remember seeing your original question Nariz and didn't comment because I didn't know what your problem was. Now that you have mentioned the roots....I'd like to comment on what I found wrong with 2 of my Rhoddies this spring.
I noticed that a couple of the smaller (newest planted) Rhoddies were not looking great. On investigation I found that the plants had been having their roots devoured by Vine Weevil grubs and had very little roots left. I did lift them out the ground - without the need for any sort of tool, they lifted out by hand.
Did you find any grubs when you lifted it out the pot?
8 Jul, 2012
OK - the plot thickens! The plant hadn't been in a poor condition for three years, Bulba, and seemed to be doing quite well - at least it quadrupled in size from the time it was purchased, but only ever had four or five blooms each year instead of the 20 or so that I was expecting, given the feeding and watering it was receiving. When I dug it out of the ground I found the root ball was still in the same shape and size as it had been when removed from its tub. Sorry Bulba - three years ago. Can't remember yesterday, let alone all those years ago!
Didn't notice any beasties, Scottish, but then I had this Phytophthera thing in my mind, so I wasn't looking for any other possibilities.
9 Jul, 2012
Your rhododendron is still pot-bound Nariz. This happens to plants grown in pots in peat and not re-potted often enough. The roots become compacted in the peat and, after planting out, won't spread out into the surrounding earth. This was the reason for the poor flowering and the poorly condition of the plant now. Do you still have it; then all is not lost. Soak the root ball in a bucket of water for a couple of days then start the slow process of teasing the roots out and breaking the root ball up. I sometimes employ the use of a wooden mallet to get things moving! You don't have to free every last root fibre but the more that you can manage the better for the plant. You can then replant it and it should recover in the next couple of years. We once found a rhododendron in the bargain corner of a nursery, only a couple of quid and severely neglected. After taking time to free up the roots it now one of the nicest rhodies in our garden.
9 Jul, 2012
Lovely advice, Bulba but, sadly - as I said - it has now turned up its leaves, gone to meet its Maker, and is an ex-plant! (Sorry Monty Python!) I have since checked on the RHS site what to do following a possible case of Phytophthera and the advice is to get rid of the old earth in the immediate root vicinity and replace with new topsoil.
I now have a Rhodo-sized area in my garden that will eventually need filling and a list from the RHS of what NOT to fill it with. Happy days! :o(
9 Jul, 2012
Gook luck with what ever you decide to plant Nariz. :)
9 Jul, 2012
But it probably never had Phytophthera, Nariz. I had advantage over Pimpernel in that you gave extra information about the root-ball.
9 Jul, 2012
Granted, Bulba but, as I said - it's all academic now as the Rhodo is no more. As I type ... it's a cloudy drizzly day and our neighbour has just gone along the lane with bits of this and that, ready to light a bonfire of all the garden waste we both dump .... and there's the smoke! Sad, but a lesson learned - and space for a new plant.
10 Jul, 2012
What was the root ball like, Nariz? When you planted the rhododendron was the pot full of tight roots and, if so, did you try to tease them out and loosen them? If so, then this could be the reason for the plants poor condition rather than Phytophthera.
8 Jul, 2012