I would like to know the composition of "tree trunk goop" for treating a hole in a river birch tree.

Howard's formula is: 1/3 diatomaceous earth (not the swimming pool kind) 1/3 soft rock phosphate, 1/3 manure compost. Mix w/water & paint on trunks, cuts. borer holes or other injuries. re-apply if washed off.
You can also buy it at Well's Bros 5001 Ave K in Plano or probably any feed store.
Plano Patty