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Plantations are often established in raw desert or abandoned agricultural land. To prepare the site, a source of water is first assured and the land then cleared of vegetation. The soil is ripped, plowed, disked, or land-planed prior to planting. In the United States it is often leveled (with surveying assisted by laser) or furrowed, as needed, for irrigation. Access roads may also have to be constructed, ditches dug, and fencing erected. In areas subject to flash flooding, dikes may have to be built to deflect runoff.
Plantation Establishment
Plantations are created using seeds, seedlings, rooted cuttings, or plantlets produced from tissue culture.
Direct Seeding. Most direct-seeded commercial jojoba fields are grown in raised beds. The seedbed is prepared (often using commercially available planters) as if for planting cotton or corn. In Arizona, experience has shown that with two planters mounted on a tool bar, one tractor operator can plant 60 acres (24 hectares) a day.
Jojoba seed varies greatly in size. One pound (450 g) of large seeds may number 300; one pound of small ones may contain 1,000 or more. Normally, large seed is preferred for planting because it produces more-vigorous seedlings during the first 2-3 months of growth. Most seeds, if properly handled, are 90-95 percent fertile. In cool, dry storage they remain viable enough for planting for 5 years or more.
Plantings are best done during the warmth of late spring or early fall. When soil temperatures are between 70°F (21°C) and 95°F (35°C), germination occurs within a week and the plants emerge above ground in about 20 days. Low temperatures delay germination, sometimes as much as several months, and may cause complete failure if the seed rots before germination can occur. Also, planting should be avoided during the hottest months.
During the first 2-3 months, irrigation must be applied constantly to maintain moisture near the soil surface, thereby ensuring good root establishment. Later, irrigation may be employed at monthly intervals to supply the field with a total of about 1.5 acre-feet (45 hectare-cm) of water. Overwatering can be disastrous.
About half the seeds produce male plants. Once these can be identified, farmers usually cut most of them out, leaving a scattering of a few strong, healthy ones for pollination. This makes room for the female bushes to grow bigger.
Seedling Transplants. To produce a seedling that is suitable for transplanting takes from 2 to 4 months in the nursery. Containers are at least 8 inches (20 cm) deep. The media is well drained and sterile to avoid fungal root diseases. Air-pruning of the vigorous taproots helps avoid the problem of the roots curling around and around in the container and refusing to grow downwards when planted out.
Where winters are cool, transplanting to the field is best done in spring or early summer. In warmer areas the early fall may be the best. The key is to get the seedlings well established before the heat of summer or the cold of winter.
Cuttings. In the United States, most jojoba plantings are currently done with cuttings. These are taken from superior bearing plants in cultivation or in the wild. Cuttings from some jojoba shrubs have demonstrated rooting rates of up to 95 percent, although this is unusual. However, many are genetically indisposed to vegetative propagation; cuttings taken from them either root poorly or fail to root at all.
Cuttings are most successfully rooted with misting techniques, using bottom heat to accelerate the process. In mist-propagation chambers kept at about 72°F (22°C), stem- and apical-wood cuttings (treated with fungicide and rooting hormone) produce roots within 3-8 weeks, depending on the season. The propagating medium is usually a mix of perlite and vermiculite. After roots have been established, the plantlets are transferred to biodegradable containers and gradually hardened off, so that planting them in the fields causes them minimum shock.
Machinery designed for planting tomato seedlings works well for planting jojoba cuttings. One grower in Arizona plants female cuttings in September or March/April and gets better than a 90-percent survival rate. He then puts cuttings of male plants into the spaces left by the females that failed to survive. Other growers plant male cuttings in a prescribed pattern from the start.
Creating a plantation by using cuttings is more expensive than by using seed. But it saves the effort and expense of roguing out and replacing unwanted plants; it gives the grower uniform plants of known sex, placement, and parentage; and it produces bushes that bear seed one or two years earlier than those from seedlings. When cuttings are cloned from superior cultivars, the yield per acre is expected to be 300-500 percent higher than that of a seed-planted field, with all its inherent genetic variability.
Cuttings are also useful for upgrading plantations that were created from seed. Replacing badly performing bushes with cuttings selected from those that perform best can more than double the overall yields.
Tissue Culture. Tissue culture techniques for propagating jojoba are available for commercial use. The economics of this procedure are uncertain, but the plantlets provide the same benefits as cuttings. Indeed, in the critical first years tissue cultured plants reportedly are the fastest growing of all planting materials.
Spacing
The optimum density for a plantation depends on the size and shape of the bushes and the management practices to be used. Time-tested prescriptions cannot be given at present. With more experience, a variety of densities undoubtedly will be found for different site types and cultivation practices.
An acre of tall, tree-like jojobas might contain fewer than 600 plants; an acre of small bushlike ones could hold perhaps 2,000 plants. (In metric units these represent 1,500 large jojobas or 5,000 small jojobas per hectare.) University of Arizona researchers aim at a density of about 900 plants per acre (4 feet x 12 feet spacing, or 1.2 m x 3.7 m), but are testing densities up to 1,450 per acre (3,600 per hectare). At this time most commercial growers are working toward a density of 1,000 plants per acre (10 feet x 4 feet spacing, or 3 m x 1.2 m).
According to Israeli researchers, jojoba plants seem capable of withstanding considerable crowding without displaying depressed growth or reduced production. This is probably because jojoba has few spreading roots to compete with those of neighboring bushes. However, crowded plants may compete for deep soil moisture as they mature and the long-term effects of crowding are unknown.
Experience suggests that one male plant can provide adequate pollination for at least five female plants. Males should be spaced throughout the plantation with consideration given to average wind speed and direction. Recently, a computer program has been developed to help calculate the best location and spacing of males for a given site.(Information from C. Niklas)
Irrigation
For satisfactory growth and production, jojoba seems to need only a third (or less) of the moisture that crops such as citrus or cotton require. Nevertheless, in most places where annual rainfall is less than 25 inches (640 mm), supplementary irrigation is needed to ensure profitable production, unless the roots can reach permanent soil moisture. Supplemental irrigation can maximize production by:
· Allowing more dense plantings;
· Ensuring that
the crop establishes well;
· Shortening the time that a young plantation
takes to reach maturity;
· Doubling the number of roots;
·
Increasing the bud formation in early spring; and
· Increasing the time
of photosynthesis.*
For these reasons, the often-quoted statement that jojoba needs little or no irrigation can be misleading. The plants do indeed need little for survival, but economic consideration may dictate that irrigation is essential. For a healthy, profitable crop in many dry areas, extra water will be necessary.
Different methods, ranging from furrow irrigation to elaborate and expensive sprinkler systems, as well as drip or underground biwall tubes, are being used. The choice depends on the availability and cost of water, the land form, and the soil type. Normally, growers install drip and sprinkler irrigation systems on sandy soils and furrow irrigation systems on heavier soils.
The average annual irrigation applied in the United States is 2-3 acre-feet of water (50-90 cm per hectare) for established plantations and 2,000-4,000 liters per plant under drip irrigation.
Fertilization
Desert soils, particularly those used for planting jojoba, are notoriously lacking in some elements. Like all crops, jojoba needs proper nutrition, but its optimum requirements are unknown at present. However, there are indications that the plant responds to nitrogen and zinc, especially on sandy soils. (Information from W. Feldman.) In general, though, most jojoba plantations have not been fertilized, and, so far at least, this has not obviously limited their productivity.
Intercropping
To provide income during the first few years while the plants are getting established, some growers plant another crop between the rows of jojoba. Asparagus, wheat, melon, barley, sesame, safflower, sorghum, and alfalfa have all been tried. In such cases the jojoba rows may be separated by as much as 15-24 feet (5-7 m). This reduces the amount of jojoba eventually produced, but intercropping suppresses weeds and helps protect the crop from desert winds that can literally sandblast the leaves off small tender bushes, or that can scarify leaf tissues, leaving them vulnerable to fungi and other disease organisms.
Intercropping, however, is not easy. The second crop can draw pests to, and water away from, the jojoba. So far, there have been many failures and few successes with intercropping jojoba in the United States.
Pests and Diseases
More than 100 species of insects have been identified on jojoba plants, but few cause any known economic damage. Thick hedgerows (normally an attractive habitat for insects and fungi) of jojoba have been growing for more than 14 years near Riverside, California, without requiring pesticides. On the other hand, spider mites, grasshoppers, and salt-marsh caterpillars have attacked some plants in Mesa, Arizona, and leafcutter ants have caused damage in parts of Latin America. And in 1985 a serious infestation of thrips and spider mites occurred in jojoba fields at Desert Center, California. These are ubiquitous pests, and similar attacks can be expected elsewhere.
On poorly drained, heavy soils, jojoba, like other crops, contracts waterborne fungal diseases - verticillium wilt, fusarium, pythium, and phytophthora, for example. In regions where soils drain well, this does not seem to be a problem. Fungal root diseases also can be a problem in nurseries. Alternaria species have been associated with jojoba, defoliating not only seedlings but also cuttings propagated under mist in greenhouses.
Wild vertebrates that may graze on jojoba foilage or fruit include birds, game animals, rabbits, and rodents. Livestock such as goats and cattle have also been known to feed on jojoba. Burrowing rodents, such as gophers, will often eat the roots. These problems can usually be reduced by fencing the fields or by setting traps.
Weeds
Weeds are the single most serious pest problem. During a plantation's early years of growth, they can be difficult to control. In the United States, Bermudagrass is one of the worst. Some growers recommend irrigating newly prepared fields to encourage the weeds to grow and then spraying herbicide before planting the jojoba crop.
The weed problem usually disappears after two years. By then, the weeds become shaded and suppressed by the growing jojoba plants.
It is the between-plant weeds that are the most troublesome; weeds between the rows are easily removed by cultivation.
Timing of herbicide application is important. Care must be taken to avoid causing the flowers (both male and female) to abort.
Harvesting
Jojoba seeds are harvested when they are fully mature. Earlier harvesting reduces the quantity of wax that can be extracted and diminishes the vigor of seedlings they produce. Jojoba is nonshattering, there is enough delay between the time the seeds mature and the time they drop to allow for harvesting the crop.
In many countries, mechanical harvesting is probably essential for commercial jojoba production. In Israel and the United States, large, over-the-row jojoba pickers - modified from grape, raspberry, and blueberry pickers - have worked reasonably well. The machines use layers of plastic fingers to flip seeds off the plants and onto belts that deliver them to containers on the harvester.
These pickers have received the most attention, but machines that suck up fallen seeds from the ground are also being tested. Vacuuming can best be done if the soil lends itself to crusting. If not, a form of net may be used to catch the seed. The system has the disadvantage that the suction may pick up dirt and rocks, but it has the advantage that the seed is mature, dry, and already dehulled when it falls off ring, and by selecting cultivars that ripen at the same time.
Pruning
Because of their low-branching habit, jojoba bushes will require pruning before mechanical harvesters can be used. Removing basal branches can get the plant "up in the air," making it amenable to mechanical harvest, but it is not yet known whether this will reduce yields. Some farmers suggest that pruning may reduce production by 20-30 percent.
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