An Archive Of Information On Some Native Fruit Species
Growing the Saskatoon - A Prairie Heritage
Article by Richard G. St-Pierre, Ph.D.
This article is a revised version of the article that was originally published in 2001 in The Cider Press 14(2): pp 19-24.)
"On the great Plains there is a shrub bearing a very sweet berry of a dark blue color, much sought after, great quantities are dried by the Natives; in this state, these berries are as sweet as the best currants, and as much as possible mixed to make Pemmecan; the wood of this shrub, or willow, is hard, weighty and flexible, but not elastic, and wherever it can be procured always forms the Arrow of the Indian ... I have dwelt on the above, as it [is] the staple food of all persons, and affords the most nourishment in the least space and weight ..." From: David Thompson's Narrative 1784-1812 - entry from June 22, 1810.
The saskatoon has long been a treasured wild fruit and a prairie tradition, being an abundant staple for prairie peoples for centuries. The saskatoon is closely related to the apple, mountain ash and hawthorn. The fruit is not actually a berry but in essence, a tiny apple. The edible, sweet fruit have a distinctive flavour with subtle almond overtones.
The latin name of the saskatoon is Amelanchier alnifolia. The genus Amelanchier belongs to the Rose family (Rosaceae - apple subfamily Pomoideae), and is comprised of about two dozen species of shrubs and small trees distributed in North America and Eurasia. The species of Amelanchier are closely related and often difficult to distinguish. The origin of the generic name Amelanchier is derived from the French Provençal name, 'amelanche', for the European species, A. ovalis; amelanche is a derivation of the Gauloise word for small apple.The North American species of Amelanchier are variously called by a number of common names, especially serviceberry, saskatoon, Juneberry, shadbush, and poirier or petites poires. The French Canadians referred to Amelanchier fruit as 'poires' because of the pear-shaped berries of some species. The common name 'serviceberry' derives from the similarity of the fruit to the service or sarvis, a forgotten English fruit (possibly Sorbus torminalis), whereas shadbush is associated with eastern species that bloom when the shad (a fish) begin to return to their spring spawning grounds. The saskatoon was first described botanically by Thomas Nuttall in 1818 as Aronia alnifolia, and subsequently re-described as Amelanchier alnifolia in 1834. The specific name alnifolia means 'with leaves like the alder'. The word saskatoon apparently was an anglicized version of the Cree name for the fruit which was Mis-sask-qua-too-mina or Mis-sask-a-too-mina (plural Sask-a-too-mina). However, it's also possible that the name was derived from the Cree name for the place where stems of saskatoon bushes were collected for arrow shafts; this name was Mane-me-sas-kwa-tan (note that the latter half of this word is saskwatan).
The saskatoon is a western North American species, ranging from the Yukon and Northwest Territories (close to the Arctic Circle), south to California, Arizona, and New Mexico, and east to Manitoba, the Dakotas and Nebraska. In the east it merges with A. canadensis near the western border of Ontario, and in the west and southwest, it merges with A. florida and A. cusickii (both of which are considered as subspecies of A. alnifolia by some botanists). The saskatoon is commonly found in open woods, coulees and bluffs, on hillsides, and along gulleys and stream banks, from near sea level to subalpine altitudes. The saskatoon is a hardy and tolerant fruit species. In habit, it may range from a low and spreading to erect and slender shrub or small tree. The saskatoon is capable of tolerating wide ranges of soil pH and texture. The flower buds have been found to have the potential for extreme resistance to low temperature injury (-50 to -60oC) at maximum hardiness. However, flowering saskatoons are susceptible to damage from late-spring frosts. In the wild, the saskatoon is considered a species adapted to areas that, in the past, were often exposed to fire. On patches of prairie that have been burned, the saskatoon vigorously produces new shoots. The saskatoon is generally grazed by deer, elk and moose. Its fruit are consumed by many birds and mammals including robins, magpies, grosbeaks, waxwings, coyotes and bears.
The horticultural potential of the saskatoon has long been recognized. In his various references to the saskatoon, the explorer David Thompson suggested that this fruit ought to be cultivated in Canada and England. The saskatoon was first cultivated in the Peace River area of northern Alberta by W. D. Albright in 1918. The first professor of horticulture at the University of Saskatchewan, C.F. Patterson, wrote about cultivating the saskatoon in 1936. In addition to its value as a fruit, the saskatoon also has value as an ornamental. Masses of showy flowers appear in the spring. Some cultivars (Altaglow and Success in particular) produce brilliant fall foliage. Other uses include range restoration, plantings for birds and other wildlife, windbreaks, and low maintenance, or native fruit landscaping. The saskatoon has not been domesticated, that is, has not undergone breeding and selection for cultivated environments. However, a number of selections having superior characteristics have been chosen from the wild, and it is this material which is being propagated and cultivated. This native fruit species is gaining importance as a commercial fruit crop on the prairies. Relatively small orchards can produce high yields and profits. Interest in cultivating the saskatoon has grown, in part, because of inconsistent wild crops and the loss of many wild plants. As well, the short, dry growing season and harsh winters typical of the prairie climate are not conducive to the commercial production of typical domesticated fruit crops such as the apple, or peach.
The Basics of Saskatoon Culture
In order to retain the characteristics of the parental stock, some form of clonal or vegetative propagation (rooting of shoot cuttings, or micropropagation for example) should be used. Shoot cuttings are best taken from the crown of the plant; if taken higher up, the capacity to root is diminished. The limitation to this method is that a large number of stock plants are required to produce significant numbers of new plants. Micropropagation requires relatively expensive and specialized equipment but a single shoot tip or bud may be used to produce a very large number of new plants. The primary advantage of seed propagation is that seeds are easily extracted from fruit and very few stock plants are required to produce large numbers of plants. The primary disadvantage to seedlings is the genetic variability within the crop, which may result in variable plant height, uneven yield and the need to cull undesirable plants many years after establishment. First generation (F1) seedlings more closely resemble the parent cultivar than second generation (F2) seedlings, which should not be planted. Regardless of method of propagation, it is very important to obtain healthy, vigorous, high quality plant material. The best quality plants are 20 to 60 cm tall, straight from rootstock to tip, free of damage, with branches intact, and having a well-developed root mass. The roots should be fibrous, and not dry. Plants having tightly-wound roots should not be purchased. Although it is best to obtain dormant plant material, most propagators supply non-dormant plants. Consequently, before transplanting newly-propagated plant material, transplants must be hardened-off so that they can better withstand the move from the sheltered greenhouse or nursery environment to harsher garden or field conditions, which may be warmer, colder, and/or drier. Hardening-off should be initiated 2 weeks prior to transplanting.
There is no single best saskatoon cultivar. It best to grow more then one cultivar since performance and fruit flavour may vary substantially with site, growing season, and cultivar. The more commonly grown saskatoon cultivars include Smoky, Thiessen or Martin, Northline, and Honeywood. The cultivar Smoky is known for heavy yields. The cultivar Thiessen is characterized by very large flavourful fruit. The cultivar Northline has a smaller stature, tends to sucker freely, but yields well. Honeywood is a good, all-round cultivar.
Soil Requirements & Site Preparation
The saskatoon will grow on a variety of soil types but prefers deep soil with good drainage and soil textures ranging from sandy-loam to clay-loam. Good growth has been observed at a wide range of soil pH. Planting sites must be free of perennial weeds. Pre-planting a green manure crop such as oats will add nitrogen and organic matter to the soil.
Plant Spacing & Row Spacing
In orchards, typical plant spacing is 1 meter; row spacing may range from 3.5 to 6 meters. Wider row spacings are important to increase airflow through an orchard so as to reduce the risk of disease initiation and development by reducing the time leaves remain wet following a rain.
Time of Planting
Recent research suggests that early-season planting dates result in increased transplant survival compared with planting dates later in the season. There is a greater risk of poor transplant survival if planting occurs after the end of June. Fall planting appears to have variable results. It's important to avoid transplanting just before or during a time of environmental stress, such as during hot, dry periods, or when there is a substantial risk of frost. Planting in the spring while the plants are still dormant will decrease the danger of plants drying out because the soil is cool and moist; slow evaporation of water from the soil, and slow growth will allow for good initial establishment. Early planting helps to increase root growth. Transplanting may be done when soil temperatures reach 5oC. The use of dormant plants allows for a full cycle of plant growth, and therefore maximal root and shoot growth, which is not the case if non-dormant plants are used.
Plants may be placed into furrows, trenches or holes in the soil using a variety of equipment. Planting holes must be large enough to easily accommodate the root mass. In clay soils, the use of an auger or similar implement can glaze the walls of a hole, thus inhibiting water drainage, root penetration, and the transfer of water. Trenches in heavy clay soil may be susceptible to poor water drainage. Plant roots should be disturbed as little as possible and should not be allowed to dry out. When transplanting, plants should be set a little deeper (5 to 7 cm) than they were in the propagation container (in colder regions, frost heaving will push shallow-set plants out of the ground; once the rooting medium becomes exposed, the plants will dry out very quickly). The soil can then be firmed around the roots to remove pockets of air. However, growers must be careful not to transplant too deeply. Research on deep-planted maple and oak seedlings has indicated a decrease in survival and stem diameter, and an increase in susceptibility to winter injury, compared to seedlings that were planted with the root collar at the soil surface. Deep-planting may also lead to girdling (strangulation) of the stem by roots. Following placement, the plants need to be watered well, and consistently, but not overwatered.
Mulches can be applied immediately following transplanting. Black plastic (2 to 3 mil, UV resistant) or fabric mulches are preferred. Such mulches effectively control weeds, retain soil moisture, and warm the soil earlier in the growing season, thus enhancing growth. Organic mulches tend to keep the soil too cool in the spring, thus having a negative impact on growth, and are labour-intensive to manage. Black plastic or fabric mulches can be applied in conjunction with a trickle irrigation system and fertilization is then done via the irrigation system. The transplants are placed in the ground first, and then pulled through a cross- or X-shaped slit in the plastic or fabric immediately after the mulch is laid. Care must be taken to avoid injuring plants during this process.
There are no well-defined recommendations for fertilizing saskatoons. Soil testing should be conducted prior to planting and soil nutrient levels should be adjusted as required for fruit crops in general. Annual soil and leaf testing and monitoring for deficiencies will provide additional information on nutritional needs within an orchard. The annual application of compost or well-composted manure may meet all nutritional requirements unless the soil is very sandy. Iron chlorosis may be a problem on heavy, excessively wet soils, or on soils with a high pH. Fertilization should not be necessary at the time of transplanting. It is widely held that a starter fertilizer high in phosphorus should be added to the soil prior to placing the plant, in the belief that this will stimulate root growth and promote rapid transplant establishment. However, studies have indicated that applications of high P fertilizers do not promote either root or shoot growth in woody plants except where substantial deficiencies exist. Excessive soil fertility may actually reduce root development and over-fertilization may cause a spurt of growth that the roots can't support. Concentrated fertilizer can burn roots and cause plant death.
Where rainfall may be inadequate, irrigation is essential for the successful establishment of a saskatoon orchard and is important to maximize yields, and to minimize plant stress and problems with diseases such as canker. New transplants should be monitored closely and irrigated every 1 to 2 days with small volumes of water, so as to ensure that the root plug does not dry out. It is very important to maintain even soil moisture levels. The root plug of young saskatoon transplants dehydrates at a similar rate to the soil near the top of the root plug, even if soil near the base of the plug is adequately moist. To prevent root damage from dehydration in newly-transplanted saskatoons, the moisture level of the soil near the top of the root plug must be monitored in order to determine if irrigation is necessary. Mature plants require a consistent supply of water, especially on sandy soils, but it is possible to water saskatoons too much. In regions where irrigation or rainfull is excessive, fruit cracking and an insipid flavour will be the result.
Past practice has dictated that pruning at planting time will improve a transplant's chances of survival and enhance subsequent growth. It is usually thought that such a practice will reduce the transplant's requirements for water because of the reduction in actual and potential leaf area. However, studies with apple, pear, peach, linden, and birch, where pruned transplants have been compared to unpruned transplants, have indicated that a minimalist approach to pruning newly-transplanted plants is the best. These studies all have indicated that topping or severe pruning at transplanting is not beneficial to survival, establishment and subsequent growth, and in fact may have substantial negative effects on subsequent root and shoot growth. The additional moisture stress resulting from leaving the shoot intact (that is, not-pruning) is more than compensated for by the additional availability of carbohydrates stored in the shoot, and the capacity to produce carbohydrates by the leaves, both of which are important to root and shoot growth. Additionally, severe pruning of young fruit trees delays the onset of bearing because of delayed growth and consequent lengthening of the period of juvenility. For the first three years following orchard establishment, pruning should be primarily associated with the maintenance of plant health and the encouragement of vigour and growth. During this period, pruning primarily involves the removal of weak, diseased, damaged and dead shoots. Low, spreading branches should be removed and the centers of shrubs thinned to keep them open and thus allow good air circulation. Subsequently, depending on the rate of growth, older wood (stems greater than 2.5 cm in diameter at the base) are thinned to improve airflow and stimulate new shoot production. Removal of diseased or damaged wood may be carried out at anytime. Pruning a large planting of saskatoons is a time consuming process. Pneumatic pruning equipment will help reduce the time an effort required for this task. Hand saws, good quality loppers, and secateurs may be all that is needed to prune a small saskatoon orchard.
Pollination & Yield
The saskatoon is mainly self-fruitful and does not require pollinizer cultivars for fruit set. Yields vary with year, location, cultivars grown, plant age, plant density, and management practices. Yields may range from 1 to over 8 kg per plant.
Weeds may be controlled through mulching, cultivation and the herbicides linuron, dichlobenil and glyphosate, all of which are registered for use on established saskatoons.
Insect Pest & Disease Control
The primary insect pest of young saskatoons is the woolly elm root aphid, which can cause significant plant losses during the initial years of orchard establishment. A soil drench of the insecticide Orthene is used to control this pest. Cultural methods of control have not been successful. During fruiting years, insect and disease control practices are essential to insure consistent fruit quality and yield. The primary insect pests of the saskatoon include the saskatoon bud moth, leaf rolling caterpillars, saskatoon sawfly and the apple curculio. IPM techniques designed for apple orchards may be suitable for control of the some of these insects in saskatoons. The primary diseases include Entomosporium leaf and berry spot, saskatoon-juniper rust and Cytospora canker. Pruning to ensure adequate air circulation, and the use of the registered fungicides Kumulus, Topas, and Nova, will help control these diseases.
Harvest, Cleaning & Sorting
Harvesting the saskatoon crop is one of the most labour intensive parts of the orchard operation. Fruit may be harvested by hand or with the aid of mechanical harvesting equipment (hand operated, pull-type or self-propelled). The hand-operated BEI Model H Harvester, developed for the blueberry industry, simply shakes fruit from branches into catch frames and works very well for harvesting saskatoons. More advanced harvesters include various pull-type and self-propelled harvesters that travel overtop of the row shaking the fruit into a catching area where fruit are automatically transferred to containers via a conveyer system. After harvesting, fruit should be cooled, cleaned and sorted as soon as possible. Fresh saskatoon fruit are very perishable and don't have a shelf life much beyond 3 or 4 days unless they are cooled and stored using modified atmosphere packaging.
Economics & Marketing
Saskatoons may be sold fresh or frozen direct from the farm gate, at Farmer's Markets, to wholesalers, to restaurants, or to processors. Some growers are also in the business of processing their crop. These processors often also purchase fruit from other growers. The price received for saskatoon fruit varies from $3.00 to $8.00 per kg depending on the year, volume sold and the particulars of the market. Fruit processors typically pay at least $4.00 per kg for frozen fruit. Small quantities of fresh fruit sold direct to the consumer generally sell for $6.00 - $8.00 per kg. Since saskatoons typically take 6 to 8 years to reach full production, the cost of establishing an orchard may take 7 to 10 years to recover. Harvesting and cleaning the fruit are the most costly parts of the orchard operation. Mechanical fruit harvesting is more economical than hand picking if the capital cost of the harvester is spread over a large enough orchard.
More information on saskatoon production may be found in: Growing Saskatoons - A Manual For Orchardists.