Dwarf Sour Cherry
(a two page guide)
Dr. Bob Bors, Assistant Professor, Department of Plant Sciences, University
(photo is of a new dwarf cherry being tested)
The University of Saskatchewan released the first dwarf sour cherry cultivar, SK
Carmine Jewel in 1999. SK Carmine Jewel was selected because of its dwarf stature.
(2m) Trees have excellent hardiness
and produce early-ripening, dark red fruit high in sugar and easy to harvest by
shaking from the tree. The U of S expects to name and release other superior
seedlings in the near future.
The dwarf sour cherry combines the small stature and excellent hardiness of
Mongolian cherry (Prunus fruticosa) with the fruiting characteristics of
sour cherry (P. cerasus) to produce small trees with fruit that look and
taste like sour cherries cultivars such as Evans, Rose,
Manual: A manual dealing with production of dwarf sour cherries is
presently being produced. It is slated for release in 2002.
Hardiness: Dwarf sour cherries were bred in zone 2b to survive winter
lows of B40°C
without damage. While SK
has proven hardy in Saskatoon and several other Saskatchewan locations, the
dwarf sour cherry is still in the experimental stage. More testing is needed,
especially in Chinook areas. Growers are advised to begin at a small scale and
expand to larger operations as more becomes known.
Spacing: Within-row spacing for mechanical (over-the-row harvesters) is
recommended at 1m while spacings of 1.5m are recommended for hand-harvested or
shaken trees. Between row spacings of 5m or more should be determined by tractor
width. Where larger implements are not being employed between-row spacings can
be substantially narrower.
Fertilizer: Many prairie soils have adequate soil fertility to sustain
dwarf sour cherries. Soil testing and fertilizer incorporation prior to planting
is recommended. Subsequent fertilizing should take place only during spring as
rapid succulent growth later in the growing season is prone to winter injury.
Watering: During the first three years watering is extremely important to
tree establishment. Irrigation is less critical for established trees. The
established orchard at the U of S is seldom irrigated. The underlying heavy clay
soil retains enough moisture to satisfy the trees
demand. Where irrigation is provided, it should be discontinued in fall to
encourage dormancy development.
Grass Cover: Grass between rows serves to reduce mud, and to compete with
trees for moisture at the end of the growing season. In dry areas it is best to
maintain grass-free alleys between rows. Similarly, establishing trees should be
kept grass and weed free. In areas with adequate moisture, grass can be
permitted to fill in below established trees. Some growers keep orchards
weed/grass free through July, but permit weeds and grass to grow in August to
reduce the available moisture supply promoting dormancy, and also facilitates
snow trap. Long grass in winter may however also provide winter cover for
rodents that gnaw bark and girdle trees.
Windbreaks: Protection to the west and north of any prairie orchard is
highly recommended. Winter damage is often a function of desiccation caused by
direct exposure to prevailing winds.
Harvest: Trees begin bearing three years after planting with respectable
crops after five years and peak capacity reached after seven. In Saskatoon SK
is harvested in late July and early August. The fruit holds well for at least
three weeks after ripening. Future cultivars slated for release should extend
the harvest season to early September.
Yield: Yield data collection is still in preliminary stages. However
preliminary estimates fall in the range of 10 to 15Kg per fully mature tree.
Pests: Deer browse winter twigs as well as leaves and fruit so deer
fencing is recommended. At the U of S we spray two to three times per season in
May and June for cherry fruit fly. Very few other pests are observed. The trees
show excellent resistance to black knot, but a few cases of bacterial canker
have been noted.
Pruning: More research is needed to determine optimum pruning techniques
for dwarf sour cherries. Until more is known, trees may be pruned to an open
centre vase, like plums, or as a renewable shrub like saskatoons. Pruning should
be undertaken in winter or early spring.
Uses and Fruit Quality: The fruit of SK Carmine Jewel
is red by mid-July, but will become almost black by early August. Because it has
bright red juice and high sugar content, it is excellent for juice, wine, or any
product where development of a Acherry pink@ colour is desired.
Cherry pies in North America are traditionally made with Montmorency
cherries, which have red skin, yellow flesh and pale pink juice. Fillings made
with these cherries are typically dyed to enhance the expected Acherry
red@ colour. Consumers used to an artificial Acherry red@ may
perceive cherries made with SK
Carmine Jewel as too dark. You may need to educate consumers that your products are made
without artificial dyes.
Motorized cherry pitting machines are difficult to find and expensive. You
may wish to buy smaller hand-operated pitting machines and sell them to
Stains: Dwarf sour cherries do not stain countertops or clothing like
other fruits. Countertops usually wipe clean, and stains wash out of clothing
with a simple cold water wash.
Market: Cherries are well loved by the public. At a recent horticulture
show 50% of people sampling the fruit commented they would eat them fresh with
no processing. Pick-your-own cherries are good for customer flow because they
follow saskatoons but precede apples.
Contacts: Many nurseries are currently propagating this cultivar with the
primary propagator being DNA Gardens, Box 544, Elnora, Alberta (403) 773B2489.
People who are new to fruit growing may consider joining one of the provincial
associations: Saskatchewan call Charon Blakley (306) 645B4447,
Manitoba call Waldo Thiessen (204) 328B8083,
Alberta call Nadine Stielow (780) 998B0481.
These groups hold conferences, tours and workshops, with members also receiving
a subscription to the Prairie Fruit Journal.
Website with photo of SK Carmen Jewel:
Pollination: Dwarf Sour Cherries are
self-pollinating so only one variety is required. Bees help improve fruit set by
moving pollen from anthers to the styles.
Saskatchewan Agriculture and Food and the University of Saskatchewan finance
the breeding and research of dwarf sour cherries.
Dwarf sour cherries required 50 years of breeding work to combine cold
hardiness, dwarf stature and good fruit quality. The efforts of Dr. Les Kerr,
Dr. Cecil Stushnoff, George Krahn and Rick Sawatzky are greatly appreciated.
Dr. Bob Bors, Rick Sawatzky and Forrest Scharf are currently involved in
breeding dwarf sour cherries and other fruit at the University of Saskatchewan.