I read an old thread on this topic and didn't quite get any ideas I haven't tried. My three different varieties of filberts are healthy 10 year old trees and I have only seen 2 filberts in all that time. I get lots of lovely catkins all over them, I'm keeping a careful eye out this year for the female flowers to make their appearance. The foliage is lush and healthy, the male catkins are everywhere. There is no sign of disease and everything else in the orchard produces like gangbusters (except for a finicky pear tree that only produces when everything is perfect) I live in the Pacific NW so I may have an issue with fog or humidity affecting the viability of the pollen??? The only other crop I've had this issue with was corn, which grew lovely healthy plants, with ears that only had one or 2 kernels on each ear. Suggestions anyone???