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.