Japanese Maples

[JontreeHI]

Any tips on a variegated j maple reverting to non variegated leaf?
I'm thinking client is over watering, but could it be a light/available light issue or/as well? Trusted Landscaper insists watering is appropriate, but ground was wet not saturated while working, also an evergreen ground cover growing in tree beds, with boxwood border.
Also seeing some Norway maples in the are that are half half, curious.
Thanks!

 

[MK146]

Is the tree mostly shaded? Variegated leaves tend to have less chlorophyll and are photosynthetically less efficient than viridescent leaves. The tree may be producing more green leaves as an attempt to compensate for lack of sunlight. It's also possible that changes in day/night temperature ranges are affecting leaf pigmentation, which may result in temporary reversion to green. Green laterals are generally more vigorous than variegated laterals, if appropriate, pruning the green laterals may help to retain variegation.

 

[JD3000]

In central Ohio Ive encountered a few common problems. The thin, delicate threadleaf varieties easily scorch in hot summers so apply supplemental irrigation and maintain organic matter to conserve soil moisture.
Manganese deficiency is common here due soil pH, free lime, and actual low soil Mn so know thy site before planting.
Japanese maple scale has gotten bad here and not just on Acer. Check the plant before purchasing and use Safari on those you find infested on job sites.
Most to many maples are oil sensitive so be wary of using them on the genus without prior experience and success.
Verticillium wilt is an unfortunate reality so check out the site and the whole neighborhood for potential disease issues.