Q: About five years ago, I planted 50+ Alberta Spruce of varying sizes. 40 of them are planted in partial shade/sun, and the balance in almost total shade.
This year, a few are developing browning. I have read that browning usually develops with lack of sun for chlorophyll production, but the ones that are browning are in the sun. The ones planted in total shade are green and growing.
What, if anything, can be done, and is this condition serious?
If they receive too much sun, it is also likely that spidermites have attacked and damaged the trees. Spidermites prefer hot temperatures, and the Alberta spruces in the sun are probably prime environments for them, whereas the ones in shadier conditions may not be.
Check the plants for spidermites and treat appropriately.