honey locust turning green

I would like some help in this area. Our Honey Logust is about 12 years old and the leaves are turning green why is this. Is it something in the soil, or something lacking in the soil? Thanks

 

This is a yellow- or reddish-leaved form?

 

Probably a Sunburst (most common non-green variety)....it's only the newest growth that exhibits the yellow colouration. As the leaves mature, they turn the regular green. So, as the summer goes on, the % green on the tree will increase and if new growth ceases for the summer (like in late summer), all the yellow will turn to green. An older tree will not be as vigorous as a young tree and will cease new growth earlier in the season which might explain why you're noticing a difference this year vs. years past.

The tree has to photosynthesize somehow.

 

Thank-you[ smivies] you are very helpful, and quick. And to Ron B. it is a yellow leaved. .

 

Vigor shouldn't be falling off markedly after only 12 years, so you might, in fact have a cultural issue that needs to be identified and addressed. Maybe it just needs to be top dressed or mulched, or the weather has been drier lately - anything causing it to make less new growth than earlier.

There should still be yellow new growth each spring and early summer, of course; if not , then your tree has apparently reverted to the typical green plant or undergone some sort of other transition.