malhomme

This is as controversial a subject as Superthrive. Some evidence proves that it does work and some evidence proves that it doesn't. Therefore, nothing has been proven. It is a plied marketing tool though, so that's why you hear so much about it. My thought is that at the worst you are simply wasting small amounts of fertilizer.

The conventional wisdom (for the "it works" crowd) is to apply foliar sprays in the morning when the stomata (on the underside of the leaves) are open and exchanging gases. This also gives time for the moisture to evaporate before pathogenic fungi find a home in this nutricious soup that would otherwise be clinging to your leaves overnight.

That said, my personal experience is that I have not seen a benifit from this regime whatsoever. I understand that certain chemicals can be absorbed into the living tissue via non-root surfaces... gibgerilen, for example... but I can't say that foliar feeding has helped my trees in the least.

Cheers,
Jim