We have a mature weeping willow tree in the backyard that has a few dead limbs that appear to have some kind of fungus growing on them. The tree has also been infestated by bugs that has caused the bark to come off the trunk. The tree has filled out with leaves beautifully this spring. Is there anything I can apply to the tree to rid the bugs, possible fungus, and heal the tree. it provides great shade for our backyard and we hope to save it.