Q.Littleleaf Linden Tree
Hello: every springtime our Littleleaf Linden blossoms into what looks like a healthy tree, yet it always has so many small branches and twigs that are dry and brittle. I keep the tree looking healthy by cutting these off, but they return proportionally as much year after year, making it very difficult to now reach the top ones. What is the cause of this and what can I do to stop it from happening?
This could be due to drought stress or more serious pests or disease.
You will need to do more inspection of the tree; it's leaves, branches and trunk.
These links may help you.
http://www.extension.umn.edu/garden/diagnose/plant/deciduous/linden/branchesdead.html
https://www.gardeningknowhow.com/ornamental/trees/linden/linden-tree-information.htm
You may also want to talk with your County Extension Office.
They may have information on specifics to your growing zone and other trees in your area.
https://www.gardeningknowhow.com/extension-search/