Fruitless Mulberry has a hole in trunk
I have 3 well established Fruitless Mullberry trees and one has a hole in the top of the main trunk about 3" in diameter. It's in an area where rain water can seep directly into the tree and possibly cause rot and/or mesquito breeding area. What can I use to plug up the hole that will slow the possibility of rot and reduce mesquito breeding? https://drive.google.com/file/d/0B-WqRTVjWRHTRzRqUl9zNEh1azQ3NkxtdTFJN2p4UE9NbGdF/view?usp=sharing
It's better not to fill the cavity or drain it. Modern arboricultural research has shown that old practices like this do more harm than good. Standing water does not increase decay, in fact it suppresses more aggressive wood rot organisims.
HOW TO TREAT A TREE CAVITY The Morton Arboretum
"In most cases, it’s best to do nothing."
"How should trees with cavities be treated? Recent research shows that it is better to leave the cavity open - remember no type of drainage, sterilization, fill material, wound paint, or scraping treatment stops decay - and simply take the necessary measures required to improve the overall health of the tree. A healthy tree has the strength to compartmentalize and wall-off decay."
Drop a BTI Mosquito dunk in the cavity periodically, which slow releases a biological control agent.
ISA Board Certified Master Arborist