Young trees being more supple don't need much pruning for wind
resistance but still may require some pruning for esthetics and to
remove branches that rub. With older trees I do prune to open the
centers for better air flow and to permit sun to enter. As to
fertilzing I do drive in those spikes for the first couple of years
but once established they're on their own. It's more important to
deeply water newly planted trees being careful not to over water.

I was just curious. With the newer closer photos it does look like
air could flow through easily. Thanks for answering my curiosity. I
over did it with the fertilizers in the past. I have used the spike
years ago. Now I just punch holes around the trees and put compost
around them a couple times a year. I do prune, but not as much as I
should. Afraid of doing more harm than good.

You are correct, overfertilizing is more harmful than no fertilizing.
Once established roots will expand to compensate for the tree's
nutritional needs. I operate from the point that fertilizing inhibits
root system maturity. Naturally one should check that the soil is
suitable for the type of tree; ph, drainage, and exposure are much
more important than fertilizing. Trees are very efficient at storing
nutrients.

I find it hard to keep fruit trees going well without fertilising even
though my soil is quite rich with high CEC. Especially the citrus need to
be fed yearly. But I am not talking about concentrated chemical
fertilisers, if I used those it might last longer. The ornamentals I don't
fertilise although most are natives; acacias, callistemons, eucalypts etc,
which are well adapted to less than wonderful soils.

David