walnut trees and stress

Scientists have found that walnut trees respond to stress in their environment by producing a chemical form of aspirin. Significant amounts of the aspirin can be found in the air around walnut trees in times of drought or unusual temperatures. The chemical aspirin was found by accident when scientists in Davis, California, set up instruments in a walnut grove to study volatile organic compounds. They noticed atmospheric increases in levels of aspirin during a time when the grove experienced unusually cool nights and hot days. The aspirin not only helps the tree recover and prevent disease, it's a communication tool to warn other plants of environmental dangers.

pollination

Walnut trees are pollinated by the wind, not by bees or other insects.

 All walnut trees are monoecious, that is bearing male and female reproductive organs on separate flowers on the same tree. Catkins (male inflorescences) are borne laterally on 1-yr wood, and pistillate flowers are borne terminally or laterally on current season's wood in spikes of typically 2-3 flowers.

Wellwood Walnut Trees

The walnut tree is well suited to cold climates. It is slow growing, with best results achieved on deep soils with good drainage. For these reasons we located our orchard at Wallace, Victoria, Australia. We planted an assortment of walnut cultivars (Amigo, Black walnut (j. Nigra), Chandler, Chico, Franquette, Gusenheim, Howard, Mayette, Serr, Vina, Wilson’s Wonder and Wybolena) partly because cross-pollination was said to give a heavier nut set and partly because we did not know which varieties would do well in our location. From the outset we practiced organic methods but sought organic certification only a few years ago. Almost twenty years down the track we are pleased with the quality of our walnuts and the development of most of our trees.

walnut trees in snow

Value Added

It is difficult to place a monetary value on the many vital services that trees provide. However, the California Department of Forestry and Fire Protection calculated that a single tree that lives for fifty years will contribute service worth nearly $200,000 (in 1994 US dollars) to the community during its lifetime. This includes providing oxygen ($31,250), recycling water and regulating humidity ($37,000), controlling air pollution ($62,500), producing protein ($2,500), providing shelter for wildlife ($31,250), and controlling land erosion and fertilizing the soil ($31,250).