We have a cottage in a very close proximity to the Black Sea (around 2 kilometers) in what is referred to as a Temperate Climate Zone environment. We have 3 old walnut trees that give a fair amount of walnuts each year. However, most of them get black and fall out from the tree prematurely. According to my grandmother, in the past, there was no such problem with the walnuts. However, with each year, more and more nuts get spoiled. The trees are very huge and it would be very hard to spray them with bordeaux spray or anything else. Has anyone else experienced such problem with walnut trees and are there some more "natural" ways to handle this?