The garden that I work at has an old hardy hibiscus that flowers prolifically with double white blooms. It is next to an old brick ice house (now storage). This year though the leaves came out and it is going progressively yellow from the RH side towards the middle. We had a very dry year with 90s arriving as early as April so everything is stressed, but the other hibiscus shrubs are coping just fine. New leaves come out fine then yellow, again one side then the other - ie lateral movement of the yellowing effect.

I have checked for bugs: none

There is no mottling associated with virus, but I have not totally ruled that out.

Doesn't look like a fungal problem.

There is evidence of a main stem being taken off/out/broken - this area is hard to get to and look at carefully though and it is several years old.

I don't think it is mineralogical as that would effect the whole shrub.

So I am down to: maybe viral and maybe Roundup contamination by some of the volunteers.

Any other clues to look for that you guys can suggest????

Thanks

Kate