My neighbour's mature rhodo has developed a health problem this spring, or at least half of it has. The trunk splits close to the ground and one branch looks completely healthy while the other has dried and yellowing leaves. I will attach photos. Has anyone seen anything like this before? Any recommendations on what to do?
Could you send a photo of the area where the trunks meet? I wonder if there is a split that has caused half of the plant to die.
Lots of otherwise tough old hybrid rhododendron plants in my part of the region have honey fungus bootlaces on their trunks, I would first check to see if the base of this specimen is infested. Otherwise if the affected half is full of lace bugs I suppose it might be possible that these are responsible. The thing to do would be to read about lace bugs on rhododendrons, see what might be expected. Including the likelihood of them building up to the point that a plant starts yellowing - but only half of it does.
Regardless what is the cause of the problem it looks like the trunk is a goner. I would remove it asap.
Based on my experience with lace bugs, I'm skeptical that they would be the cause of this rhodo's problems. To my eyes, there is little physical evidence of lace bugs on either side of the leaves. There should be much more stippling on the upper surface - instead of being uniformly yellow. On the underside, many more actual insects and fecal matter should be visible. Then the question - why would the damage be on only one side of the plant? I think the honey fungus theory is definitely worth exploring although it seems strange that it would be restricted to only one half of the plant. Also, I agree with Sundrop that the dead half should be removed asap.
