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Tree Fruit Culture and Cultivars in North Dakota (H327 (Revised))

Growing your own fruit can be fascinating and fun. Many different kinds of tree fruits, including apple, pear, plum and cherry, can be grown successfully in North Dakota.

Revised by Tom Kalb, Horticulturist NDSU Extension Service


Moving west and north across the state, conditions become less favorable for growing fruits because of extreme temperatures and reduced rainfall. However, with proper selection and the necessary cultural practices, the home gardener can harvest ample fruit most seasons.

Cover page

Protecting fruit trees from harsh winds in winter and summer cannot be overemphasized. City dwellers usually have a more favorable environment for establishing fruit trees than rural residents because the concentration of buildings and shade trees can greatly reduce wind velocity. On farms, the fruit tree planting is best located within the building site. Wind protection may be provided by hills, buildings or shelterbelts. Shelter is necessary from all directions except the east.

Fruit trees should be planted at least 40 to 50 feet from farm shelterbelts to prevent breakage from snowdrifts and reduce competition between the fruit trees and shelterbelts for sunlight, soil moisture and nutrients. In town, where backyard space may be limited, locate fruit trees away from large shade trees for similar reasons. Most fruits do well on any fertile garden soil that has good surface drainage.

How to Select a Fruit Tree

A consumer visiting a local nursery often is overwhelmed with the selection available. Choosing a good tree from the inventory is not as simple as you might think. Following certain criteria will help make a good selection. They are hardiness, tree size, branch number, branch angle and, to help get the properly selected tree off to a good start, planting time.

Hardiness

Hardiness is the most critical factor when selecting varieties for North Dakota. The U.S. Department of Agriculture’s Hardiness Zone Map (Figure 1) is based on extreme winter temperatures. Most North Dakotans live in Zone 4a (minimum winter temperature of minus 25 to minus 30 F). Consider this map as a guide, not a hard and fast rule. Exposure to wind, alkalinity and soil moisture also can affect the adaptability of a variety. Asian pear, sweet cherry and peach are not reliably hardy.

Figure 1

Figure 1. Hardiness zone map of North Dakota.

Cultivars

Gardeners in northern areas will benefit from choosing the most hardy and earliest-ripening cultivars. See Pages 5-7 for a complete listing and description of recommended cultivars. Cultivars are listed in order of ripening.

Tree Size

Look for trees that are at least ½ inch in diameter just above the graft union. Experience has shown that trees smaller than this do not establish as well as larger ones. However, bigger is not always better! If a tree is allowed to get too large (1-inch diameter or more) at a nursery, a significant part of the root system may be damaged or removed in digging. This will give an unbalanced ratio between the top and root system of the tree, creating problems in establishment and survival.

Branch Number

Ideally, a tree should have three to five symmetrically spaced branches that are about 4 to 6 inches apart starting about 2 feet above the graft union.

Well-branched trees can be developed by the homeowner even if only healthy, unbranched trees between 5 and 6 feet tall are available. After planting and before the buds break, the tree can be cut about 36 inches above the graft union. A healthy tree will respond with several branches developing below the cut, allowing the homeowner to make selective cuts later on for good branch distribution.

Branch Angle

Wide-angle branches (60 degrees from the central axis of the tree) will be the strongest. Vigorous, upright branches – often called water sprouts – will not be contributors to the overall production and strength of the tree. Branches that are at a wider or flatter angle will produce fruit earlier than sharp-angled branches. Overall, the tree should have a pyramidal shape to make efficient use of the sunlight.

Planting Time

The urge for spring planting is overwhelming in North Dakota. You can meet this desire easily by planting bare-root stock as soon as the frost is out of the ground. Experience has shown that bare-root planted trees, if healthy, will exhibit vigorous growth and establishment the first year. Some nurseries order bare-root stock to offer to early shoppers, then pot the remainder for sale throughout the growing season.

The fall planting season often is overlooked. At that time, the trees are moving and storing carbohydrates in their root systems. Consequently, no visibly active growth is witnessed above ground. All the action is taking place in the roots, which continues until the soil temperature reaches about 40 F. Fall-planted trees often will exhibit greater vigor the following spring than spring-planted ones in comparable situations.

Dwarf Apple Rootstocks

Dwarf trees are smaller than standard trees because of the influence of the rootstock on which they are grafted. Dwarf trees bear crops a few years earlier than trees grown on standard rootstocks. They are easier to prune, spray and harvest. They can be incorporated into nearly any home landscape.

The hardiness of apple rootstocks limits their use to Zone 4 in North Dakota. Sheltered sites with expected snowfall are best.

Budagovsky 9 (Bud.9) is the hardiest rootstock and will grow trees up to 10 feet tall. It resists fire blight. The rootstock M.9 is one of the most common dwarf rootstocks used in the U.S., but it is susceptible to fire blight and is only marginally hardy. The hardiest of the East Malling series of rootstocks, M.26, will grow a semidwarf tree, but it is susceptible to fire blight. All of these rootstocks need to be staked.

The most popular dwarfing rootstock, M.7, is not quite as hardy, but it is used in many Zone 4 orchards. It will develop into a semidwarf tree that grows 12 to 15 feet tall. It is grown as a free-standing tree except in windy sites.

Dwarf apple trees are planted so the graft union is at least 2 inches above the ground. This will prevent the upper portion of the graft (scion) from establishing roots that will reduce the dwarfing effect of the rootstock.

A 10-foot-long, ¾-inch electrical conduit pipe is the most common staking material. Pound the stake 2 feet deep into the ground a few inches from the tree.

Many nurseries in North Dakota sell apple trees grafted onto ‘Dolgo‘ crabapple rootstock. These “standard” trees are hardy and vigorous but will be slow to set fruit (approximately five to seven years before the first good yield). These trees must be pruned vigorously to prevent them from getting 20 feet tall or taller.

Pollination

Many tree fruit cultivars cannot set fruit with their own pollen, so you must select and plant two different cultivars to ensure fertilization. Apple, crabapple, pear, American plum, apricot and cherry plum will set more fruit if two or more cultivars are present. Pie cherry and European blue plum cultivars are self-fruitful and can set fruit on their own.

Spacing

Apple trees should be spaced for easy cultivation and full tree development. For trees on standard rootstocks, minimum spacing is 20 by 20 feet and preferably 25 by 25 feet. Semidwarf trees can be spaced approximately 15 feet apart and fully dwarf trees approximately 8 to 10 feet apart.

Plum, cherry and apricot trees should be spaced 10 to 15 feet apart. Cherry plum trees should be spaced 4 to 8 feet apart.

Caring for a Fruit Tree

Planting

You can plant dormant bare-root fruit trees early in the spring, while you can plant potted nursery stock throughout the growing season.

When planting bare-root trees, dig a hole larger than the root spread of the tree to avoid crowding or bending the roots. Take care when planting potted trees that are growing and in full leaf to prevent the loss of soil around the roots when removing the container. Always remove containers before planting. Do not place soil amendments and fertilizer in the planting hole.

For apple, crabapple and pear, locate the graft (the bulge near the union of root and top) 2 inches above the soil level. Trees of stone fruits may be planted so their graft is at or slightly above the soil surface.

Tamp firmly. Leave a depression around the tree and water thoroughly. The lowest branch should be located on the southwest side of the tree to reduce sunscald problems.

Pruning

Minimal pruning is done at planting. For branched trees, remove broken branches. If branches are rubbing against one another, trim out the least desirable branch. The tree may be trimmed back to 1 foot above its tallest side branch, making sure the top of the “central leader” remains the highest point of the tree.

For nonbranched “whip” trees, cut the trunk at 30 to 36 inches. This will stimulate the first flush of scaffold branches at that point.

A young tree needs little pruning except to select proper main branches. The first branch should begin about 30 inches from the ground.

In the next 24 inches, develop the first series of major scaffold branches (Figure 2, Page 4). Four branches, one each facing a different direction (north, east, south and west), is ideal. These branches coming out of the trunk should resemble spokes coming out of a wagon wheel.

Figure 2

Figure 2. Pruning for strong-structured apple trees.

Maintain a 24-inch gap between this group of scaffold branches and the next. This will maximize sunlight and air movement between the sets of scaffold branches. As the tree grows, another 24-inch gap, followed by third set of scaffold branches, is developed.

When the tree reaches fruiting age, annual pruning will help maintain a healthy, well-structured tree and encourage annual bearing. On all fruit trees, prune all suckers that originate from the rootstock.

Branches with narrow V-shaped crotch angles should be pruned and avoided. These crotches tend to split under the weight of a fruit crop.

Vertical shoots (water sprouts) in the canopy are not productive and clutter the tree. Remove these shoots every year.

Plum, cherry plum and apricot produce their best fruit crops on relatively young growth. Prune these trees more severely.

The proper time to prune is in the early spring after severe cold weather has passed and before new growth occurs. However, broken and diseased branches should be removed any time of the year. Sterilize pruning tools between cuts with household bleach diluted to 10 percent (1½ cups to 1 gallon of water) if removing branches infected with fire blight.

Mulching

Cultivation is essential in establishing young fruit trees. In town, one or more trees can be grown in the lawn or along the edge of the property as screening trees for backyard summer privacy. A circle of cleanly cultivated soil 5 to 6 feet in diameter should be maintained around the trunk of each tree.

Shredded bark mulch should be placed around the tree. The mulch should be minimal at the trunk and then reach an ultimate depth of 3 or 4 inches around the perimeter of the ring. Rock mulch will trap heat and should not be used.

For orchard plantings on farms, a permanent grass cover crop such as bluegrass, orchardgrass or fescue may be used if water is available. Spray strips with glyphosate to kill weeds within the row.

Watering

Watering is critical at the time of planting. Thoroughly soak the root area. The orchard will need to be irrigated regularly for at least two years. Water weekly, giving young trees 3 to 5 gallons each.

Fertilizing

Spring is the best time to fertilize. A good way to monitor the fertility of the soil is to see how much new growth is produced each year. The annual growth of a tree can be seen as the glossy tissue from the tip of the branch to a dark scar that encircles the branch. Young fruit trees should grow about 18 to 24 inches per year and then decline to about 10 inches per year when they get fruit-bearing age. If trees are not getting this growth, consider a soil test and fertilizer treatment.

Staking

Staked trees will bear earlier and produce higher yields than unstaked trees. Staking will protect trees from damaging winds and keep the root system stabilized in the soil. In the case of grafted trees, staking prevents the scion from snapping off the rootstock.

Protecting From Sunscald

Sunscald is a very serious problem on fruit trees in North Dakota. Injury usually occurs in late winter or early spring when bright afternoon sun warms the southwest side of the trunk and exposed lower branches. The absorption of heat by the dark bark activates the growth of cells beneath the bark. These cells may be killed later by freezing.

Sunscald injury can be prevented by installing white tree guards around the trunks to reflect the sun’s rays. Another means of protection is to paint the southwest sides of the trunk with a white latex water-based paint diluted to 50 percent.

Managing Wildlife

Rabbits and mice might become a problem in the winter, especially if their food supplies are low. Put a cylinder of ¼-inch mesh hardware cloth around the trunk for protection. The cylinder should reach up to the first major branch, approximately 24 to 36 inches high, and be buried a couple of inches in the ground.

A wildlife repellent sprayed on the limbs will protect the rest of the tree.

For deer, horticulturists recommend an 8-foot-tall fence for large-scale plantings. Fencing made of nylon is relatively affordable and will work for several years. Metal fencing is longer-lasting but more costly.

Spraying

The easiest way to control insects and diseases is to maintain a good sanitation program. This involves collecting dropped leaves and fruit from the planting. Burn or destroy all prunings, leaves and dropped fruits to avoid harboring pests.

Insecticide sprays may be needed for high-quality fruit. Insect traps are available to monitor for codling moth and apple maggot. If the pest is not there, you don’t need to spray.

Foliar diseases, such as apple scab and rust, are most likely to occur when the spring season is wet. The most critical sprays are early in the spring when leaves are emerging. Prune trees every March to maximize sunlight and air movement in the canopy. This will reduce the humidity in which most fungi thrive.

Follow the recommended rates of application and allow the proper interval between the last spray and fruit harvest.

Apple

Apple is the most popular tree fruit in North Dakota. Cultivars are self-unfruitful (more than one cultivar is needed for fruit set). Growers in Zone 4 should consider dwarfing rootstocks, especially if snow cover is likely during the winter. In general, early cultivars are good for fresh eating but do not store well. Cultivars listed below are hardy to Zone 3 unless noted otherwise.

Apple Chart

Crabapple

Its tart flavor makes this fruit popular for canning and making jellies. A crabapple tree will pollinate/fertilize an apple tree and vice versa. Most varieties are partially self-fruitful but will produce higher yields in the presence of another apple or crabapple cultivar. Hardy to Zone 3.

Crabapple Chart

Pear

Pears are susceptible to fire blight; monitor closely and prune out infected branches. Plant more than one cultivar for best yields. The Canadian cultivars work well together with Golden Spice, as do Summercrisp and the South Dakota cultivars. Hardy in Zone 4 unless noted otherwise.

Pear Chart

Plum

All cultivars below with the exception of Mount Royal require more than one cultivar to set fruit. These cultivars may be grafted on American plum rootstock to promote hardiness and vigor. Space trees 10 to 15 feet apart. Hardy in Zone 3 unless noted otherwise.

Plum Chart

Cherry Plum

These cultivars were developed for the northern Great Plains. They are extremely hardy (Zone 3), resist drought and will bear fruit after one to two years. Small trees grow up to 8 feet tall and can be spaced 4 to 8 feet apart. They are self-unfruitful, so plant more than one cultivar.

Cherry Plum Chart

Cherry

Pie cherries are used for pies, sauces, jams and breads. Ripe cherries can be eaten fresh. Self-fruitful (only one cultivar needed). Naturally dwarf trees can be planted 10 to 15 feet apart. Hardy to Zone 3 unless noted otherwise. Sweet cherries are not hardy in North Dakota.

Cherry Chart

Apricot

Apricots bloom very early, so plant them out of frost pockets. The trees are naturally dwarf and can be set 10 to 15 feet apart. They are self-unfruitful. The Minnesota cultivars work well as a team, as do the Manitoba cultivars.

Apricott Chart

Propagation

Cultivars of fruit trees do not reproduce true from seed. In other words, the seeds of a ‘Honeycrisp‘ apple will not produce ‘Honeycrisp‘ apples. The seeds have the maternal genes of ‘Honeycrisp,‘ but we often do not know where the pollen came from. Because apple varieties do not fertilize each other, we are sure the pollen did not come from ‘Honeycrisp‘; instead, it came from another type of apple or crabapple.

Even if a variety is self-fruitful, such as a pie cherry, the seedling will differ somewhat from its parent and will take several years before it bears its first fruit. In the vast majority of cases, propagation from seed results in trees of inferior fruit yield and quality.

Instead, superior individual trees (such as the original ‘Honeycrisp‘ tree in Minnesota) are identified, named and then propagated by asexual means (grafting). A bud/twig of a ‘Honeycrisp‘ is grafted onto another branch/root and we are assured the bud/twig will produce ‘Honeycrisp‘ fruit.

Grafting is a way of combining a bud or twig of one plant with a branch or root of another so that a union forms and growth continues. A hardy rootstock is a must for our climatic conditions.

Bud Graft

Many of the apple trees and all of the stone fruit trees (plum relatives) sold in the area nursery trade are propagated by a type of graft called budding. It could be described as the “transplanting” of a single bud of a desired variety into the stem of a hardy seedling rootstock. Budding is done in late July or early August.

Scion Wood

Dormant scions are used for the cleft and bark grafts. The grafting is done in early spring, usually before growth starts (April–May 10). Collect scions of 1-year-old wood in the fall, winter or early spring. They may come from trees whose fruit you desire – perhaps those of neighbors or friends. Scion wood also is available from nurseries.

Scion wood should be placed in closed plastic bags and stored under refrigeration (32 to 40 F) until used. Do not store scion wood in the freezer.

Cleft Graft

The cleft graft often is used to topwork young trees two to three years after planting. This graft utilizes the technique of inserting a section of stem with two buds (the scion) into the stock. To prepare the scion piece, make a 1- to 1½-inch-long, smooth, sloping cut on both sides of the scion base to form a wedge (Figure 3-A).

Prepare the stock for receiving the scion. On young trees, select three to five well-spaced scaffold branches, preferably with wide angle crotches. Cut back selected branches to be grafted 12 to 18 inches from the trunk (Figure 4-A). Remove all other branches and side branches.

Next, insert a sharp knife 1½ to 2 inches deep into the center of each stock (Figure 3-B). Insert prepared scions into the stocks. Generally, the stock is larger in diameter than the scion; therefore, take care to set the scion to one side instead of on center (Figure 3-C).

Carefully align the cambium tissue of the scion and the stock. The cambium is the layer of growing cells that is just under the bark and outside of the wood (Figure 3-D).

Wrap this graft union (Figure 3-E) carefully with a good grade of rubber electrician’s tape. As the graft grows, the tape stretches and eventually deteriorates without girdling the new growth.

Figure 3     

Figure 3. The cleft graft is simple but effective.

Figure 4

Figure 4. The bark graft.

Bark Graft

The bark graft can be used with larger stocks (up to 12 inches in diameter) than for cleft grafting, but the scions are similar in size. Several scions can be inserted around the stock. The stock is cut off as for cleft grafting, except it is not split through the center.

Bark grafting must be done when cell division in the stock has begun, usually late April or early May in North Dakota, allowing the bark to separate readily from the wood. At this time, the bark is said to be “slipping.”

Cut the base of the scion on one side with a long, smooth, sloping cut about 1½ inches long, going completely through the scion so that it comes to a point at the base (Figure 4-C). Make a vertical cut about 1½ inches long going through the bark in the stub of the stock (Figure 4-B). Slightly loosen the bark at the top of the cut and insert the wood surface of the scion base next to the wood of the stock. Push the scion down behind the bark to the extent of the cut on the scion base (Figure 4-D).

Use rubber electrician’s tape to secure the scion in place and cover the entire cut surface of the stock with tape (Figure 4-E). If other tapes (such as masking tape or plastic tapes) are used, they must be cut after the union develops to prevent girdling. You do not need to remove them. For topworking, place scions every 2 to 4 inches around the stock stub. As with cleft grafting, the intent is usually for only one to remain eventually.

You can give the electrician’s tape and exposed scions additional protection by painting them with interior latex water-base paint to prevent drying.

This publication was authored by Larry J. Chaput, retired; Ronald C. Smith, retired; and Dave DeCock, retired.

 


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