I concur with
@Pitoon assessment. Decidedly pale. Using Iron chelation will be a short term remedy. Adding Miracid regularly and/or Osmocote will be a long term help.
Two thoughts occur to me.
It feels to me almost like the bacteria decomposing the pine part of your base media is pulling all the excess nitrogen out of the system…including from the pumice and lava, which have a low & medium CEC, while the bacteria is busy doing the decomposing of the bark…. this is a long way of saying your normal fertilization definitely needs tweaking upwards as the system is out of balance. Adding fertilizer will to change the available nitrogen balance so there is enough nitrogen available for your azalea to get healthy and also to keep the bark decomposing bacteria fed.
So starting with Miracid will give things an immediate boost and following up with Osmocote Plus will add a long term slow release component. Both are complete fertilizers (with micronutrients including Fe, Mg etc). You’ve enough time before fall to get the system back in order.
Second thought… how much sun is this azalea getting?
Cheers
DSD sends