Growing Apples

APPLES CAN BE GROWN IN A WIDE RANGE OF SOIL FERTILITY LEVELS

Apple Breeding

In this hybrid of an orchard apple with a red- fruited crabapple cultivar, the pulp is of the same colour as the peel.

Like most perennial fruits, apples are ordinarily propagated asexually by grafting. Seedling apples are different from their parents, sometimes radically. Most new apple cultivars originate as seedlings, which either arise by chance or are bred by deliberately crossing cultivars with promising characteristics. The words “seedling,” “pippin,” and “kernel” in the name of an apple cultivar suggest that it originated as a seedling. Apples can also form bud sports (mutations on a single branch). Some bud sports turn out to be improved strains of the parent cultivar. Some differ sufficiently from the parent tree to be considered new cultivars.

Some breeders have crossed ordinary apples with crabapples or unusually hardy apples in order to produce hardier cultivars. For example, the Excelsior Experiment Station of the University of Minnesota has, since the 1930s, introduced a steady progression of important hardy apples that are widely grown, both commercially and by backyard orchardists, throughout Minnesota and Wisconsin. Its most important introductions have included ‘Haralson’ (which is the most widely cultivated apple in Minnesota), ‘Wealthy,’ ‘Honeygold’ and ‘Honeycrisp.’ The sweetness and texture of ‘Honeycrisp’ have been so popular with consumers that Minnesota orchards have been cutting down their established, productive trees to make room for it, a heretofore unheard of practice.

Starting An Orchard

Apple orchards are established by planting two to four year old trees. These small trees are usually purchased from a nursery where they are produced by grafting or budding. First, a rootstock is produced either as a seedling or cloned using tissue culture or layering. This is allowed to grow for a year. Then, a small section of branch called a scion is obtained from a mature apple tree of the desired cultivar. The upper stem and branches of the rootstock are cut away and replaced with the scion.

Rootstocks affect the ultimate size of the tree. While many rootstocks are available to commercial growers, those sold to homeowners who want just a few trees are usually one of two cultivars; a standard seedling rootstock that gives a full-size tree, or a semi-dwarf rootstock that produces a somewhat smaller tree. Dwarf rootstocks are generally more susceptible to damage from wind and cold. Full dwarf trees are often supported of posts or trellises and planted in high density orchards which are much simpler to culture and greatly increase productivity per unit of land.

Some trees are produced with a dwarfing “interstem” between a standard rootstock and the tree, resulting in two grafts.

After the small tree is planted in the orchard, it must grow for 3- 5 years (semi-dwarf) or 4-10 years (standard trees) before it will bear sizeable amounts of fruit. Good training of limbs and careful nipping of buds growing in the wrong places, are extremely important during this time, to build a good scaffold that will later support a fruit load.

Location

Apples are relatively indifferent to soil conditions and will grow in a wide range of pH values and fertility levels. They do require some protection from the wind and should not be planted in low areas that are prone to late spring frosts. Apples do require good drainage, and heavy soils or flat land should be tilled to make certain that the root systems are never in saturated soil.

Pollination

Apples are self-incompatible and must be cross-pollinated to develop fruit. Pollination management is an important component of apple culture. Before planting, it is important to arrange for pollenizers, cultivars of apple or crab apple that provide plentiful, viable and compatible pollen. Orchard blocks may alternate rows of compatible cultivars, or may have periodic crab apple trees, or grafted-on limbs of crab apple. Some cultivars produce very little pollen, or the pollen is sterile, so these are not good pollenizers. Quality nurseries have pollenizer compatibility lists.

Growers with old orchard blocks of single cultivars sometimes provide bouquets of crab apple blossoms in drums or pails in the orchard for pollenizers. Home growers with a single tree, and no other cultivars in the neighbourhood can do the same on a smaller scale.

During the flowering each season, apple growers usually provide pollinators to carry the pollen. Honeybee hives are most commonly used, and arrangements may be made with a commercial beekeeper who supplies hives for a fee. Orchard mason bees are also used as supplemental pollinators in commercial orchards. Home growers may find these more acceptable in suburban locations because they do not sting. Some wild bees such as carpenter bees and other solitary bees may help. Bumble bee queens are sometimes present in orchards, but not usually in enough quantity to be significant pollinators.

Symptoms of inadequate pollination are excessive fruit drop (when marble sized), small and misshapen apples, slowness to ripen, and low seed count. Well pollinated apples are the best quality, and will have 7 to 10 seeds. Apples having fewer than 3 seeds will usually not mature and will drop from the trees in the early summer. Inadequate pollination can result from either a lack of pollinators or pollenizers, or from poor pollinating weather at flowering time. It generally requires multiple bee visits to deliver sufficient grains of pollen to accomplish complete pollination.

A common problem is a late frost that destroys the delicate outer structures of the flower. It is best to plant apples on a slope for air drainage, but not on a south facing slope (in the northern hemisphere) as this will encourage early flowering and increase susceptibility to frost. If the frost is not too severe, the tree can be wetted with water spray before the morning sun hits the flowers, and it may save them. Frost damage can be evaluated 24 hours after the frost. If the pistil has turned black, the flower is ruined and will not produce fruit.

Growing apples near a body of water can give an advantage by slowing spring warm-up, which retards flowering until frost is less likely. In some areas of the U.S.A., such as the eastern shore of Lake Michigan, the southern shore of Lake Ontario, and around some smaller lakes, this cooling effect of water, combined with good, well-drained soils, has made apple growing concentrations possible. However, the cool, humid spring weather in such locations can also increase problems with fungal diseases, notably apple scab; many of the most important apple-growing regions (e.g. northern China, central Turkey, and eastern Washington in the U.S.A.) have climates more like the species’ native region well away from the sea or any lakes, with cold winters leading to a short, but warm spring with low risk of frost.

Home growers may not have a body of water to help, but can utilize north slopes or other geographical features to retard spring flowering. Apples (or any fruit) planted on a south facing slope in the northern hemisphere (or north facing in the southern hemisphere), will flower early and be particularly vulnerable to spring frost.

Pests And diseases

The trees are susceptible to a number of fungal and bacterial diseases and insect pests. Nearly all commercial orchards pursue an aggressive program of chemical sprays to maintain high fruit quality, tree health, and high yields. A trend in orchard management is the use of Integrated Pest Management (IPM), which reduces needless spraying when pests are not present, or more likely, are being controlled by natural predators.

Spraying for insect pests must never be done during flowering because it kills pollinators. Nor should bee- attractive plants be allowed to establish in the orchard floor if insecticides are used. White clover is a component of many grass seed mixes, and many bees are poisoned by insecticides while visiting the flowers on the orchard floor.

Among the most serious disease problems are fireblight, a bacterial disease; and Gymnosporangium rust, apple scab, and black spot, three fungal diseases.

The plum curculio is the most serious insect pest. Others include Apple maggot and codling moth. For other Lepidoptera larvae which feed on apple trees, see List of Lepidoptera which feed on Malus.

Young apple trees are also prone to mammal pests like mice and deer, which feed on the soft bark of the trees, especially in winter. Growers usually sheath juvenile trees with wire mesh to protect them.

Apples are difficult to grow organically, though a few orchards have done so with commercial success, using disease-resistant cultivars and the very best cultural controls. The latest tool in the organic repertoire is to spray a light coating of kaolin clay, which forms a physical barrier to some pests, and also helps prevent apple sun scald.

Commerce And Uses

Forty-five million tonnes of apples were grown worldwide in 2002, with a value of about 10 billion U.S. dollars. China produced almost half of this total. Argentina is the second leading producer, with more than 15-percent of the world production. The United States is the third leading producer, accounting for 7.5% of world production. Turkey is also a leading producer. France, Italy, South Africa and Chile are among the leading apple exporters.

In the United States, more than 60-percent of all the apples sold commercially are grown in Washington state. Imported apples from New Zealand and other more temperate areas are competing with U.S .production and increasing each year.

Apples can be canned, juiced, and optionally fermented to produce apple juice, cider, vinegar, and pectin. Distilled apple cider produces the spirits applejack and Calvados. Apple wine can also be made. They make a popular lunchbox fruit as well.

Apples are an important ingredient in many winter desserts, for example apple pie, apple crumble, apple crisp and apple cake. They are often eaten baked or stewed, and they can also be dried and eaten or re-constituted (soaked in water, alcohol or some other liquid) for later use. Puréed apples are generally known as apple sauce. Apples are also made into apple butter and apple jelly.

Health benefits

An old proverb attests to the health benefits of the fruit: “An apple a day keeps the doctor away.” Research suggests that apples may reduce the risk of colon cancer, prostate cancer and lung cancer. Like many fruits, Apples contain Vitamin C as well as a host of other antioxidant compounds, which may reduce the risk of cancer by preventing DNA damage. The fibre content, while less than in most other fruits, helps regulate bowel movements and may thus reduce the risk of colon cancer. They may also help with heart disease, weight loss and controlling cholesterol, as they do not have any cholesterol, have fibre (which reduces cholesterol by preventing reabsorption), and are bulky for their caloric content like most fruits and vegetables.

A group of chemicals in apples could protect the brain from the type of damage that triggers such neurodegenerative diseases as Alzheimer’s and Parkinsonism. Chang Y. “Cy” Lee of Cornell University found that the apple phenolics, which are naturally occurring antioxidants found in fresh apples, can protect nerve cells from neurotoxicity induced by oxidative stress. The researchers used red delicious apples from New York State to provide the extracts to study the effects of phytochemicals. Lee said that all apples are high in the critical phytonutrients and that the amount of phenolic compounds in the apple flesh and in the skin vary from year to year, season to season and from growing region to growing region (November/ December 2004 issue of the Journal of Food Science). The predominant phenolic phytochemicals in apples are quercetin, epicatechin, and procyanidin B2 (PMID 14558772).

The seeds are mildly poisonous, containing a small amount of amygdalin, a cyanogenic glycoside, but a large amount would need to be chewed to have any toxic effect.

Pesticide contamination is linked to an increasing number of diseases, and they are mostly found on the outside of fruits and vegetables. Washing or peeling before eating may reduce pesticide intake but peeling will also reduce the intake of the beneficial nutrients.

This information has been run in previous Lincoln Leader and Enterprise-Leader newspapers.