The Almond in California

by R. H. Taylor

Fig. 7.—Almonds planted twelve feet apart. Trees in very weak condition and almost entirely defoliated by mites before harvest. The few nuts ripening on the trees are small “sticktights.” Photo taken September 21, 1915.

Distance.—Almonds in most soils should be planted 30 × 30 feet on the square. In rich, deep soils the trees quickly fill the intervening space, the roots occupying the entire soil area long before the tops touch. In poor, shallow soils, or soils deficient in available moisture, the trees may not occupy the entire area above ground, but the roots will require more horizontal feeding space to enable them to make the size trees and bear the crops that they should.

Trees planted too close together often abstract the moisture from the soil before the growing season is completed. This shortage of moisture, with the aid of mites, commonly called red-spider, causes the loss of the leaves long before they normally should drop. Under such conditions the fruit buds are unable to make the vigorous growth which they should. These weak buds are unable to endure the degree of frost or other unfavorable conditions that stronger ones withstand without serious injury.

The trees must have plenty of sunlight and air. If planted too close, the trees tend to grow too high, each one striving for the light which is only available from above. In [figure 7] the upward tendency of the trees is clearly shown. Such trees, if pruned as they ought to be, have a much greater tendency to send out numerous water-sprouts than trees which have plenty of room for the tops to expand laterally. After the tops of the trees interlock and shut out the sunlight from the lower portions, the smaller branches and fruit spurs in those parts gradually weaken and die, and eventually the entire crop is produced on or near the tops of the trees, where direct sunlight is available, as shown in [figure 7]. The excessive upward growth of the trees, with the consequent forcing of the fruit bearing to the top, not only greatly increases the difficulty and cost of pruning, spraying and harvesting, but reduces the possible bearing surface of the trees.

Setting the Trees.—The utmost care is necessary in setting out the trees to secure a uniform stand of vigorous trees. The trees are planted much the same as other deciduous orchard trees, but care must be used to spread the roots well to secure a thorough compacting of the soil around all the roots, and to see that the trees are not planted deeper than they were in the nursery.

CULTURE

Soil Handling.—The almond is one of the most exacting of fruits as regards its cultivation. The assumption is very often made by growers that because the tree will live through periods of prolonged drouth, it will also thrive under careless or poor methods of cultivation. That this is entirely erroneous may be inferred from the fact previously referred to that the almond draws more heavily upon the plant food of the soil for the ripening of its crop than any of the common orchard fruits. Experience has abundantly proved that many almond orchards are not bearing profitable crops because the requisite soil constituents are not available in sufficient quantities during the long growing season. The reasons for this condition may be one or several. First, there may not be sufficient moisture available throughout the season, or it may not be distributed evenly or in sufficient amounts throughout the entire soil area. Second, there may be insufficient aeration of the soil; and third, there may not be sufficient humus to fix the soluble plant food in the soil and render it readily available as needed by the roots.

Proper distribution of moisture in sufficient quantities is essential to secure adequate solution of the mineral elements needed by the roots for the use of the tree in all its parts. Sufficient aeration is needed to provide for the normal oxidation and weathering of the soil particles, and also for the respiration of the roots themselves.

There seems to be no question about the value of spring plowing and cultivation to put the soil in good physical condition, but many growers apparently question the value of summer cultivation. Though the surface of the soil appears to be unchanged after a period of several months, the fact is entirely overlooked that the structure of the mulch has been gradually changed and capillarity to the surface has been restored. The result is that evaporation takes place so rapidly from soils in such a condition, as well as from the leaves of the trees, that long before the end of the season the moisture is practically gone.

The methods and tools used are much the same as for other orchard trees and it is only necessary to call attention to items likely to be neglected. Spring plowing should vary in depth from year to year to avoid the formation of an impervious plow-sole. The depth to plow ranges from a minimum of six inches to ten or twelve inches or more as desirable. Summer cultivation should be kept up at least once a month, and preferably oftener, throughout the summer months and the soil should be stirred to a depth of four inches to provide a mulch sufficient to hold the moisture effectively in the hot, dry climates where almonds are grown. The actual number of cultivations necessary will depend on the types of soil. Harness with projecting hames or broad singletrees or with projections of any kind to catch on the branches or bark of the trees should never be used in an orchard.