Updated: Oct 11, 2020
Those points in your cut celery and the long strings that get caught in your teeth are the vascular tissues.
The majority of tree decline I am seeing the past few years is a combination of tree roots buried too deep (under mulch or soil) and insufficient watering. Focusing on water - in decades prior, we could go the whole winter without watering our trees. There was plenty of winter precipitation in the form of rain and snow and the trees moved into winter without any water deficit. Now, the water deficit happens y