I'm talking Ceratopetalum gummiferum here

I have put some pics online
http://www.innerweb.com.au/ourgarden...tmasbushes.htm but to describe
the problem, we have 5 in a row. They start out ok on the left, then
deteriorate moving toward the right. I can't work out any difference in
soil, sun or drainage characteristics between the rhs and lhs. We did a ph
test - pretty uniform, the soil on the happier plants showed the same
slightly acid reading as the soil on the sad plants, so we added some lime -
that was about 6 weeks ago.

We keep them well seesol'd and blood and boned, also a little osmocote 'for
natives'. The problem is displayed by the brown tips on what otherwise
appears a healthy leaf. The larger the percentage of brown, the worse that
tree looks overall - even the happiest of the bushes have developed slight
brown tips. We have had the trees I think nearly two years. Last year they
were perfectly happy - all uniform and well.

We are in Brisbane, but the plants are in a sheltered courtyard - they
receive some direct sunlight (each bush gets about the same amount) but it
is mostly filtered.

Any advice would be appreciated