In the time of Solomon, the English walnut was widely referred to as the ‘Fruit Of The Orient’. It was called one of the noblest of nuts and is now cultivated everywhere in the higher parts of the region. The trees need near watercourses, village fountains, and wells to survive and flourish. So, the walnut tree was appreciated for its delicious nuts and valuable timber.
Solomon’s “nut garden” or walnut pavilion is supposed to have formed part of his extensive gardens at Ethan, six miles from Jerusalem. Although no trace remains of Solomon’s gardens, the locality is still beautiful. Its fine shade, fragrant leaves, and delicious fruit made it a prime favorite in Solomon’s garden.
Although not introduced into England until about 350 years ago, the walnut is now popular there and is commonly known to us as the “English” walnut. This is because the English brought the walnut to North America, which is why they are called “English”. The British helped widely spread the cultivation, changing the walnut production history in middle and southern Europe, California, and the Southeastern United States. Its fruit is one of the most important of all present-day commercial nuts.
Originally, walnuts were planted more rapidly in the southern counties of California. Even as late as 1936, 65% of all the bearing acreage was in the southern counties. Only 35% were found in the areas north of the Tehachapi Mountains. Between Los Angeles and Bakersfield. Then the picture began to change as one of walnut production history’s most dramatic horticultural moves took place. Since that time, the center of walnut production has shifted from the south to near Stockton in Middle California.
Today, less than ten percent of the bearing acreage lies in the southern counties, while more than 90% lies in the central and northern areas. There are less than 1,250 acres of walnuts in Los Angeles County now and less than 500 acres in Orange County. Ventura County, which used to be the largest producer with 25,000 bearing acres in 1942, now has less than 6,525.
The reasons for the shift were many. Some southern California orchards became decadent, and others were of low-yielding varieties: subdivisions rushed into walnut-growing areas. Better growing sections, improved irrigation and pest control methods, and better types were helping the spread to the north, where greater yields were evident.
Back in 1936, the non-bearing acreage was concentrated in the northern part of the state with 73% total, while the southern area had only 27% of the state we non-bearing acreage. The 1963 totals shifted dramatically, with less than two percent of the non-bearing acreage found in the Joaquin and Sacramento valleys have experienced the greatest growth. Now 42% of the non-bearing acreage lies in the San Joaquin Valley and 32% in the Sacramento Valley.
Today, 99% of the American walnuts grown commercially are in California. The neighboring states of Oregon and Washington contribute with the other 1%. The Willamette Valley in Oregon and Southern Washington are where that last 1% comes from. Walnuts are grown in other states but are not of commercial significance. Many different varieties of walnut trees have been imported to America. But, it is the English Walnut that dominates retail sales. Specifically, the other types that customers enjoy are Carpathian Walnuts in New England and Black Walnuts in the Southern American states.
Walnuts do best on soils where roots can develop evenly to a depth of 8 to 10 ft. In addition to good topsoil, subsoil must be free of rock, impervious clay, or layers of gravel.
Soil type alone cannot determine a good site for a walnut orchard. An auger, soil tube, or posthole digger should be used to check to a depth of ten feet. A few feet beneath the surface, solid rock or compact subsoils with a mottled color indicating poor aeration and drainage may be found. Besides affording few or no pores large enough for roots to enter, this subsoil layer often supports a water layer that further restricts root growth. Some excellent surface soils are underlain by loose gravel and coarse sand with such large pore spaces that excessive aeration and drainage permit little or no root growth.
Unfortunately, not much can be done to improve unfavorable soil conditions. Blasting has not been effective. Often it merely increases the trouble by compacting the soil further. In a few cases, “subsoiling” has helped where the waterproof layer is not thick and is close to the surface. Generally, this practice can not be recommended. If the orchard is already established and is declining because of subsoil problems, thinning the trees is the only helpful practice.
Excessively high temperatures will not limit the production of walnuts. Occasional temperatures around 100° F. may cause sunburning of the hulls of the nuts and poor quality of the kernels within. Sunburn may result in dark-colored kernels with black specks or even fail to develop. Depending on the time of the season when the high temperature occurs.
The lack of excessively high temperatures has helped give walnuts more desirable light-colored kernels than those produced in hot areas. However, a certain amount of warm weather is needed to make good-quality kernels. Temperatures of 80°-90° near harvest time have planted well-filled kernels with high oil content. For example, the entire summer of 1948 was cold, and walnut kernels were excessively shriveled and had a low oil content. Walnuts produced by the same trees in warm seasons had kernels with high oil content and little or no shriveling.
Under mild climatic conditions, walnut trees are slow in attaining full dormancy in fall or early winter. As a consequence, early cold periods may injure or kill many trees.
Early maturity is desirable for growers. Walnuts in California mature nearly a month earlier than in Oregon, giving California shippers an advantage in getting nuts or the market to meet the early demand. Oregon growers mature early because varieties that bloom early in Oregon are highly subject to injury from spring frosts. In Oregon, growers need a variety that does not bloom too early but has a growing requirement. Some progress has been made in the search for such a variety.
Popular present-day varieties include the Payne, Eureka, and Hartley. Nearly 26% of today’s bearing acreage is still in Franquettes, 20% in Paynes, 7% in Placentias (primarily in the American South), and 22% in Hartleys. In the history of walnut production statistics, these other varieties have little effect on the commercial walnut industry.
Each variety has distinct advantages which make it desirable, and each is most adaptable to particular climatic and growing conditions. All types are mixed, however, in marketing, and only experts can tell the difference between them. Many other varieties have been and are being grown. New ones are constantly being tested and improved.
Oregon growers must continue to search for a variety more resistant to cold injury than any now grown commercially. Progress has also been made in this direction. A description of several Oregon varieties follows:
Up to the present Franquette has been the standard walnut variety in Oregon. Franquette has several good points in its favor but has some objectionable characteristics. It is a reasonably heavy producer, and the kernels are exceptionally light in color.
Franquette has the following undesirable characteristics: it matures too late for harvesting and processing in time to meet early market demands. The kernels are inclined to be somewhat astringent. The tree is susceptible to cold injury because it becomes dormant late in the fall.
Whole nuts average about 42% kernel. The light color of the kernels is the best selling point for the Franquette as grown in Oregon. This same variety grown in California under higher temperatures does not produce kernels as light in color.
Harvesting walnuts in Oregon is more complicated than in California. In Oregon, fall rains usually begin before harvesting is completed. Mud, fallen wet leaves, and fragments of split hulls increase the harvesting problem. Machine harvesting in Oregon has not been practiced appreciably because of the difficulty of getting machinery through wet orchards. Wet leaves are difficult to remove by present field cleaners or harvesting machines. Most walnuts in Oregon are still hand-harvested.
Walnut harvesting in California begins in mid-September and continues into late November. Methods used depend upon the size of the particular orchard and the available equipment and crew a grower has. The variety, size of trees, and yield per acre also influence the harvesting method.
Harvesting starts as soon as the walnuts can have the hulls removed. As practically all at once or over several weeks, depending upon the varieties of walnuts at harvest.
Mechanical shaking has replaced handshaking and the boom type. shaker is generally used. It is a one-man type of operation. Operators with skill are required to prevent excessive bruising or injury of the tree limbs.
Both handpicking and mechanical picking are done in California walnut orchards; the method depends upon the size of the orchard, labor available, equipment available, yield per acre, and proportion of crop being harvested in going over the orchard one time. Because of labor shortages, mechanical pickers improvements, and increasing wage rates, machines bring walnuts to market.
The rate at which a mechanical picker works depends upon the type of machine, the condition of the ground and how the walnuts were positioned by raking for the mechanical operation, the amount of foreign material on the ground, and the number of men required in a crew for optimum operation of the whole process. Hulling will have a requirement if they have a loosened green hull that has not fallen off the walnut. Many years ago, it was done by hand, but today’s mechanical machines hull and wash the walnuts as they are brought in from the orchards.
After hulling and washing, the grower must thoroughly dry the walnuts to prevent deterioration. Most growers dry by mechanical dehydration, even those with only a few walnut trees and who do not own a dehydrator, usually share a neighbor’s rather than practicing the old-time sun-drying method, which depends upon the weather. The walnuts are then well started on the first part of their journey to the consumer.
The orchard floor must be prepared for harvesting, whether nuts are handpicked or machine-harvested. For machine picking, a smooth orchard floor is required.
Preparation of the orchard floor for harvesting usually consists of thorough cultivation in mid-September. This cultivation is followed by rolling or dragging. All walnuts do not mature and fall simultaneously, so shaking or several pickings are required. Sometimes second harvesting is necessary even when tree-shakers are used.
Oregon walnuts drop freely from their hulls if moist enough during nut maturity. The first picking usually includes the poorest filled nuts. They get picked up before the harvesting of the main crop. Walnuts should be harvested as soon as possible after they drop. Nuts that drop on wet ground, leaves, and green hulls rapidly become so discolored that they are acceptable to the trade.
The same is true of harvested nuts left wet in the sack, for more yellow stain comes from the divider membrane between the two halves of the kernels and the old packing material that lines the shell.) While the yellow stain does not affect flavor, it detracts from the appearance and is objectionable to the trade. It can be removed by soaking kernels in water and drying them immediately. In this process, however, much of the brand sheen of the kernels is lost.
Mechanical tree-shakers have become fairly common in Oregon. Approximately 75% of the nuts on the trees show split hulls. The trees should be shaken, and the nuts harvested immediately. Under these conditions, some nuts will drop with the hulls still adhering, so the general practice is to run all the nuts through a walnut huller and washer before drying.
In recent years, some growers have used hand rakes with wooden pegs to rake walnuts into piles, eliminating the need for pickers to crawl over the entire ground area. Some growers scoop these piles of nuts into portable field cleaners, but these machines are not perfected, so they are not in general use.
If the farmers shake the trees too early, many immature nuts will make it to the harvest. When dried, they often have a reddish shell and cannot be bleached satisfactorily.
Hand pickers are usually paid either by weight or measure. Some growers pay by the hour, but payment on a piece-work basis has proved more satisfactory. Pickers are often rewarded if they stay until the harvest is completed.
The change in walnut production history from the 1950s to today is the change in technology between when the walnuts hit the orchard floor to the point they reached the market. Artificial drying of bulk walnuts is necessary for commercial distribution. Often this is a commercial operation, but some growers maintain their walnut driers or use driers purchased for other purposes.
Many drying methods are used in California, but the underlying principle is usually the same. Warm air circulates the individual nuts at temperatures not exceeding 90° to 100° F. Commercial driers finish with a moisture content of about eight percent. Walnut kernels containing this moisture or less will snap when broken.
According to Statistical Report, the 1965 commercial walnut crop in the world’s leading producing countries (exclusive of the Soviet Bloc and Communist China) was estimated at 160,000 short tons, in-shell basis. The 1965 harvest was 81,600 tons for the seven specified foreign walnut producers. Three thousand nine hundred tons below average and 6,100 tons below the 1964 crop. The foreign crops were all smaller than in 1964. Except in Iran and Italy, the harvest was slightly higher than in 1964. U.S. walnut production, at 78,400 tons, was 7% above average but 13% below the large 1964 cгор.
Walnut exports in 65 of the seven major exporting countries (excluding the Soviet Bloc and Communist China) were estimated to have totaled 48,200 tons in shell. This is 7% above 1965 but 5% below the 1963 average. Foreign countries’ exports in 1965 were at 44,600 tons.
U.S. exports of walnuts in 1965 totaled 3,600 tons in-shell basis. 2,866 tons in-shell and 291 tons shelled. compared with 1,730 tons (1,327 tons in-shell and 161 tons shelled) in 1963-64. U.S. imports of walnut kernels in 1964-65 totaled 1,330 tons compared with 1,345 tons in 1963-64; imports of in-shell walnuts are negligible. 1965-66 exports should be up because of increased emphasis on exporting.
Current numbers from the USDA on the 2022 California walnut production are forecast at 720,000 tons. Down a mere 1% from 2021 production numbers. These numbers come from counting productive acres in California, which still represent 99% of the commercial walnut industry crop. So, the acreage taken up by walnut crops is going down along with the productivity of these acres.
