_Sour-sap._—This is one of the so-called “physiological diseases” and is quite common with the almond. It is most frequently found where trees are planted in heavy or poorly drained soils. The inability of the almond to endure standing water around its roots for any length of time and particularly so after growth commences in the spring, renders it especially liable to sour-sap when planted in soils where excess water from the late winter and spring rains cannot be readily drained away. The direct cause of the trouble is sudden changes in weather from warm to cold after growth commences, which checks the flow of sap very suddenly, causing stagnation, cracking of the bark and then fermentation. With an unusually strong flow of sap in trees in wet soils, such climatic changes cause unusually severe disturbances in the normal functioning of the trees. The affected trees ordinarily show the disease first in the spring when gum may be seen oozing from the bark of the trunk or main branches, and sometimes even from the smaller branches. Small or large branches may die, and in severe cases the tree may die soon after having commenced to leaf out strongly. On cutting through the bark to the wood and peeling back, a strong sour odor is noticeable. The cambium layer appears brownish or reddish in color and often masses of gum may be found between the bark and the wood. Mild cases may not be serious enough to show on the outside of the tree and only portions of the cambium layer may die. The sudden dropping of the blossoms or young fruit may in some instances be attributable to sour-sap. All affected parts on smaller branches should be cut back to healthy wood, while on the main branches or trunk, where only a small portion or one side is affected, it is best to clean out the dead bark and paint the bared wood with a protective covering until new bark can cover the spot. At the same time every effort should be made to remedy the soil-moisture conditions which were largely responsible for the trouble in the first place. _Fruit-drop._—The same conditions which cause sour-sap may cause fruit drop. It may be caused by lack of pollination due to improper mixing of varieties or to rain during blossoming. Frost may also produce the same thing by killing the germ in the young fruit. In such cases, the fruit may remain on the tree for one or two weeks after the injury occurs before falling, and in some cases, may even appear to continue its development for a short while. INSECT PESTS _Mites._—Commonly called red spiders. There are two kinds of mites that do much damage in almond orchards, the brown or almond mite and the yellow or two-spotted mite. Both are common in all parts of the state and are the worst pests the almond grower must regularly face.