We had a warm, moist early spring which is generally bad news for our number one enemy, walnut blight. Blight is a bacterial infection which enters the flower and pollen during rain events and develops through the season to cause unsightly black marks on the green husk and eventually on the shell of the nut. It develops further to actually cause the kernel to turn into a black mush. These nuts usually fall early and are picked up before harvest. To compound our problem this spring, our airblast spray unit suffered a major fault and it took 5 weeks for parts to arrive and get it repaired, thus defeating our efforts to reduce the risk of blight. Anyway, we have a reasonable crop coming with not too much blight evident yet.
I have attached some photos of the flowers and the catkins which produce the pollen. Walnuts are self pollenating although they generally end up pollinating each other because the production of flowers and pollen don’t occur at the same time on the one tree. The flower has tiny yellow sepals which are like sticky tongues. The flower base is not much bigger than a match head and the 3 or 4 sepals are only about 2 to 4 mm long. The catkins are about 100mm long and knobby. These knobs open up and produce pollen, a bit like coral polyps opening up.