Phaedrine Stonebridge said:
snip

I thought the foliage looked a
bit chlorotic and we were just exploring how to get trace elements to
them when this happened. The previous owners did appear to have used a
lot of chemicals on the lawn; they had a contract with one of those
places. Both sprays and pellets were used according to receipts in the
house book. Given that we are not having this problem in the other
garden (which did not used to be lawn), perhaps that is also part of the
problem?

If the lawn clippings were carted off and replaced mainly with high nitrogen
lawn fertilizers, it is very possible that you have an area that's been depleted
of some critical micornutrient or even a macronutrient (like potassium).

Lots of people 'strip-mine' their soil by sending off the fallen leaves and
grass clippings, and don't replace much more than the nitrogen. (Trees
recover most of the nutrients from their leaves before they drop, but not
all of them.)

--
Pat in Plymouth MI

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)