Rosaceae – (the rose family)
The Saskatoon cultivars originated from its wild form Amelanchier alnifolia, encompassing about 25 diverse species which may grow from 0.5 m to even 15 m high. In the wild, the Saskatoon can be found in the north-east part of the United States and the south-west regions of Canada. Due to similar climatic conditions in those regions it has adapted itself exceptionally well to the Polish climatic conditions. In winter, it sustains even –40oC, and its flowers do not show any signs of frostbites even when the temperature drops down to minus 5oC or minus 7oC.
The Saskatoon grows into a multistemmed shrub or a small tree (depending on a variety) and usually reaches the height of 2 m; its shrubs develop more or less a wide-stretching habit.
The Saskatoon develops green leaves which are almost oval in shape and serrated on their margins.
It displays flowers gathered in trusses, which are white in hue and self-pollinating (a single variety plantations can be grown, cross-pollination also possible), and they bloom in the second part of April; their flowering lasts approximately from seven to ten days.
The Saskatoon bears berry-like oval pomes which sometimes can be slightly elongated in shape with visible dry sepals. They become deep blue or black, sometimes purple in hue, covered with a strong waxy bloom and gathered in bunches. Their size depends on the variety of the Saskatoon, but they usually reach 5–15 mm in length and weigh 0.5–1.3 g. They are juicy and sweet, with a nice flavour and their juice is carmine in hue. They ripen approximately 45–60 days after blooming, usually from the end of June till the first part of July, i.e. before the blackcurrant and the blackberry harvesting. An individual shrub gives a crop of 8–12 kg. The Saskatoon pulp is juicy and in order to get more juice, its berries should be left after harvesting for another seven days to let them overripe. The Saskatoon berries contain a lot of biologically active substances such as vitamins A, B and C, sugars (8–12%, mainly glucose and fructose), apple and lemon acid (0.5%), up to 1% of pectin, 0.9% of tannins, carotene, coumarin, copper and cobalt. They are also considerably rich in anthocyanins (up to 1000 mg%) which act as preventive agents against many diseases, mainly against cancer. They contain a small amount of proteins (up to 9%) and a small amount of fat (up to 5%). According to some research findings, the Saskatoon berries contain more minerals and boast better dietary and healthful properties than the high blackberry. As much as 100 g of the frozen Saskatoon fruit contains approximately seven times more calcium and iron, and four times more potassium and protein than the high blackberry. The Saskatoon berries are recommended after radiotherapy and antibiotic therapy. They positively affect the central nervous system, have beneficial effects on sleeping and decrease over excitability. Infusions of Saskatoon flowers tone up blood vessels and thus prevent the development of varicose veins and heart diseases.
The Saskatoon is not demanding, it thrives in any soil and in all positions. It tolerates all types of soil except for boggy and marshy terrain, and dry sand. It prefers slightly acidic and slightly alkaline soils (pH 6.2–7.5).
The Saskatoon likes fully lit positions and gives poor crops when grown in shade. On commercial plantations, rows should be directed towards north-south to provide ample sun for the shrubs.
The Saskatoon is native to the central-west Canada, where in summer the temperature reaches +30oC, and in winter it drops even down to –45oC. The above climatic conditions are similar to those in Poland and that is why it can be grown in any part of our country.
• irrigation water
The Saskatoon does not require additional irrigation. Plants with a well developed root system tolerate even a long-lasting drought; they survive adverse growing conditions better than other fruit species. Their roots grow even 140 cm deep and are wide-spreading, which helps the plant to find water during a drought period. Maintaining proper soil moistness is especially important in the first two to three years after planting, since the shrubs do not manage to quickly develop their root system well.
Proper soil preparation is extremely important since the Saskatoon plantations remain on the same site for many years. One of the basic nurturing procedures includes getting rid of perennial weeds. It is also advisable to provide the plants with all the necessary nutrients by adding manure in the dose of approximately 30t/ha or sowing green fertilizers (lupine, phacelia or mustard) to facilitate their proper growth. The field in which cereals were grown is a place for growing the Saskatoon. Apart from the above mentioned, the soil analysis should be conducted and all its recommendations followed and implemented. The initial fertilizing is usually similar as in the blackcurrant or the chokeberry cultivation. In light soils, 60–80kg P2O2/ha and 100–120 kg K2O/ha are used. In fertile soils, the dose should be decreased by 20–25%. It is recommended to conduct nitric fertilization right after planting and flowering in the dose of 30–40 kg/ha.
It is best to plant young Saskatoons in spring, regardless of whether the seedlings are bare root or were grown in pots. The Saskatoon seedlings are planted in holes and placed in soil as deep as they used to grow before; the soil around the plant should be compressed and irrigated. The spacing depends on the growth strength of a given cultivar and the way of training; however, it is similar to that in the chokeberry cultivation. For the combine harvesting the best is 4.5 m x 0.75 m spacing, i.e. 3000 plants/ha, while for home gardens 3.5–4.0 m spacing between rows and 1.0–1.5 m spacing in a row are recommended.
After planting, the seedlings are shortened by one third of their length to help the shrub grow more vigorously. They can also be shortened in their second year, so that the shrub has 10–15 sprouts. After the third year of cultivation, when the Saskatoon enters the period of intense fruit bearing, its height should be kept at 2–2.5 m to help the fruiting develop along the whole length of stems. Thinning out is conducted not earlier than after the seventh year of cultivation.
The Saskatoon berries ripen form the end of June. In sunny weather, it is best to harvest them in two times. If it is colder, the Saskatoon berries are harvested gradually as they ripen. They are good for the combine harvesting – extremely high harvesting precision can be maintained and both shrubs and the fruit remain undamaged after such harvesting.
DISEASES AND PESTS
The Saskatoon is hardy. Sporadically only some varieties can be attacked by mildew. In Poland, the Saskatoon is not yet grown for such a massive scale as in Canada, where different pests are found to attack it. The following, among others, belong to the most dangerous pests: Anthonomus quadrigibbus, Hoplocampa montanicola, Epinotia bicordana, Cremona cotoneaster and Eriosoma americanum. The above pests have not been found on the Saskatoon in Poland, although they may appear with its increased popularity of cultivation. To date, some damage caused by weevils and grubs, as well as the animals of the deer family, hares, mice and birds – which willingly feed on sweet Saskatoon berries – have been observed.
USESThe Saskatoon is extremely popular and widely used in Canada. Its berries are enjoyed raw and appreciated as a valuable material for commercial processing into jams, preserves or liqueurs. Its juice possesses a lovely carmine hue which is good for colouring other beverages and preserves. The Saskatoon berries are also good for freezing, they can be added to yoghurts, desserts and cakes, and eaten as dried fruit. In herbal medicine, infusions of the Saskatoon flowers or the Saskatoon liqueurs are recommended to regulate the heart functioning. Apart from the above- mentioned, the Saskatoon can be used in hypertension as a supportive medication.
Świdośliwa olcholistna (Amelanchier alnifolia) Nowy gatunek krzewów owocowych w Polsce, S. Pluta, E. Żurawicz, D. Kucharska, 2014