The soft, moist atmosphere of western Oregon, so favorable to the
English walnut, seems wholly unfavorable to pests that destroy the crop
in other climates. A crop has never been lost or materially injured in
Oregon through these sources; in fact, so free are the Oregon trees of
such enemies that little thought or attention has been given to this
phase of the subject. In a few localities where caterpillars have
attacked the foliage they have been quickly eradicated by an arsenic
spray. Fumigating will kill insect life. A bacterial disease that has
made its appearance in California has not been seen in this state.
Winter spray of lime and sulphur will kill moss and lichens, which are
about the only parasites that attempt to fasten on Oregon walnut trees.
[Illustration: _Old Walnut Trees Planted About 1850 Near McMinnville, on
the Yamhill River_]
[Illustration: POLLINATION