Kingsville boxwood leaf splotching and discoloration

I have just begun to notice this splotching and beige discoloration of the leaves on both of my kingsvilles during the past couple of days.  Any advice regarding diagnosis and subsequent treatment will be greatly appreciated.  Many thanks!

Tom

Tom that appears to be some sort of chemical over spray. Please tell us about anything you have sprayed either on or near and your watering habits. What about other trees close to these?

Hi Tom,  We are getting extreme heat in Minnesota and I've been very careful not to water foliage.  I would imagine the boxwood leaves are holding water on their leaves with the result of sun burns.  It would be helpful to move your boxwoods to shade or use small handheld watering cans to give moisture to just the soil.  You will have to move the boxwoods to shelter after a night rain.

Good luck,
Norma

The sun burning wet leaves has been a commonly held belief and there is finally some research to put this myth to bed or does it. Here is some research that proves it is a myth. MYTH

But not so fast that was on smooth surface leaves. And here is some research on hairy leaves that proves it is NOT A MYTH.

So guys and gals based on this if the liquid drop is flat on the surface of the leaf then no burn. But if there are hairs that hold the drop above the leave then there will be some minor burning.

Please note that this is also true for human skin. Water on smooth skin - no burn, but if you are hairy then there will be some burning. (interesting)

just my 1.3 cents worth.

well now thats certainly a first... both the wife and i are correct !!!

(i said no burn - she said burn...)

and as an aside, i had a knowledgeable friend tell me to keep my one lone boxwood in the shade regardless...
seems happy as can be under a 50% shade cloth

My thanks to you all...