Yellow Needles on JBP

[BirchMan]

Hi All,

I'm wondering what's causing the yellow tinge to this semi-mature JBP. It's the first season it's really had that colour, and while it's quite vigorous with spring growth, I'd like to keep it in optimal condition.

It's been in the foam box for 5 years - the box has large drainage holes cut at the bottom and i think this is one of the grow-box situations I've got right (drains well, nice open organic substrate). I've typically fed with dynamic lifter but have recently tended towards synthetic soluble ferts.

You may be able to make out on the left in the image the other JBP that has normal coloured dark green needles for comparison.

Thanks.

[Bonsaifan]

Birchman it might need a dose of iron chelate ? I have similar problems with citrus in pots...

[shibui]

When I see this here it is usually nutrient related but you have already stated you are feeding regularly Iron is one cause of yellowing foliage, Nitrogen is another.
5 years is a fair while in the same mix. I wonder if it is still allowing nutrients to penetrate properly? Mostly the pines that go yellow here are the ones that have not been repotted for a few years.
I would try a couple of feeds of soluble fert (check that it has trace elements in it) and see what happens.

[BirchMan]

Thanks guys, I'll give it some minerals and N.