There is still much debate about pruning paste. Contemporary tree care professionals consider the application of a tree wound dressing unnecessary.
This view is endorsed by Royal Horticultural Society studies although the RHS do suggest dressing wounds when pruning trees with Coral Spot.
Apparently there are other exceptions: trees prone to silver leaf infection - cherry , peach, apricot, pear and apple. In some instances pruning paste is used purely for cosmetic purposes or to relieve the conscience of the pruner (for hurting the tree).
If you are an orchardist growing the above trees prone to Coral Spot or silver leaf infection Paul Berry from Sanctuary Honey is developing an organic pruning paste using bees wax as a base (instead of asphalt).
Paul currently produces a fully certified, organic Manuka honey at Santuary Honey so he is well qualified to produce a tree wound dressing utilizing similar techniques.