Q: What is causing the pachysandra under my white oak to be yellow versus the same stuff across the sidewalk that looks fine? Do I need fertilizer?
A: Is the Pachysandra you’re talking about new, or has it been there a while? If it’s new, I would not fertilize yet. You’re right in thinking that the oak tree may be responsible. Large trees suck everything out of the soil. Eventually, supplemental fertilizer might help, but for now I recommend letting it sit f to see if it establishes on it’s own.