I have a group of Pachypodium lamerei by the front of my house, and the largest and oldest of them ( 12 years old, about 8-9 ft tall) has suddenly started doing this. The others are unaffected. I cannot imagine that it might be dying but I can see no reasonable explanation for this. ANY Ideas?? I can't get close enough to the crown to check for bugs but can't see anything moving in there. The last of the groups of leaves is visible here in the center and it is also looking like it is going downhill.

Poor thing! I can only think of bugs sometimes insidiously crawling from inside. Reminds me of one of my Beucarnea Recurvata when it started going downhill...as well as my upright Sedum, doing similar, though did not find anything even after I checked on the roots.

Any changes on your temps/weather? I notice my desert rose is thinking it is Fall, starting to dry out its leaves when we had a sudden 10 degree variance. So maybe your pachy is just starting to wind down for Fall..though a bit early I think..but then again weather is crazy these days.

I have a group of five of which this is one; the others are all doing fine. I don't think it's the weather....

Hetty,
I know nothing about Pachypodium lamerei. Does it do this anyway come winter months? By winter I mean the cooler months you get. If this is some thing different, Then I would use a systematic like Bayer 3 in 1. Which you feed to the roots and it takes care of fungus, bugs, and a mild fertilizer. Couldn't hurt.
Stush

not lightning, huh?

P. lamerei does lose its leaves in the winter, but we are talking four plants here and only one of them is doing this. I like the suggestion of using the systemic Bayer 3 in 1. It couldn't hurt at this stage. Thanks