Q.Holly shrub is dropping its leaves
All of a sudden this last week our holly tree is dropping its leaves. We’ve had it for for years with no problems. Any idea?
Sudden leaf drop is likely an infestation or disease issue.
I've included a link that may help you determine the exact issue.
If you determine the cause, use the treatment as listed.
If you are unable to determine a cause, treat the plant with Neem Oil. Neem Oil works as both an insecticide and fungicide.
Remove and dispose of the dead leaves around the plant.
Here is a link with more information.
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
I do want to mention that it is possible that plants can be affected by accidental herbicide overspray. If neighbors or even lawn companies have recently sprayed, this could be a possibility. In this case other plants would show the same symptoms.