u/Adorable-Force-9211

This weeping willow planted in northern Adirondacks has significant sentimental value - it was planted by my dad with kids shortly before he died. It’s been growing well in the 10+ years since we planted it, but lately the lower branches seem dead. This is a picture I took yesterday - so it’s still beginning of Spring here, but you see the issue. Is there a problem? What can I do to help?