Bonsai Nut
Nuttier than your average Nut
I don't have any scientific information to share about foliar feeding, other than to ask the question - if trees take up nutrients from the soil on an "as-needed" basis, and a tree is already getting all the nutrients it needs via a robust and regular soil fertilizing program, what possible benefit could foliar feeding provide?
Feeding aside, there does appear to be a benefit from spraying certain oils/films on leaves and foliage to protect from wind and sun. There are numerous products out there that provide this benefit (WiltPruf, Wilt Stop, et al.) I notice a short-term benefit to my junipers when I spray with neem oil - even when they aren't suffering from fungus or pests.
Feeding aside, there does appear to be a benefit from spraying certain oils/films on leaves and foliage to protect from wind and sun. There are numerous products out there that provide this benefit (WiltPruf, Wilt Stop, et al.) I notice a short-term benefit to my junipers when I spray with neem oil - even when they aren't suffering from fungus or pests.