Healthy Apple Fruit

Apples were brought to North America by colonists in the 17th century,  and the first apple orchard on the North American continent was planted in Boston by Reverend William Blaxton in 1625. The only apples native to North America are crab apples, which were once called "common apples".  Apple varieties brought as seed from Europe were spread along Native American trade routes, as well as being cultivated on Colonial farms. An 1845 United States apples nursery catalogue sold 350 of the "best" varieties, showing the proliferation of new North American varieties by the early 19th century. In the 20th century, irrigation projects in Eastern Washington began and allowed the development of the multibillion dollar fruit industry, of which the apple is the leading product. 

In the wild, apples grow readily from seeds. However, like most perennial fruits, apples are ordinarily propagated asexually by grafting. This is because seedling apples are an example of  extreme heterozygotes, in that rather than inheriting DNA from their parents to create a new apple with those characteristics, they are instead significantly different from their parents. Triploid varieties have an additional reproductive barrier in that 3 sets of chromosomes cannot be divided evenly during meiosis, yielding unequal segregation of the chromosomes. Even in the case when a triploid plant can produce a seed, it occurs infrequently, and seedlings rarely survive. Because apples do not breed true when planted as seeds, grafting is generally used to produce new apple trees. The rootstock used for the bottom of the graft can be selected to produce trees of a large variety of sizes, as well as changing the winter hardiness, insect and disease resistance, and soil preference of the resulting tree. 

Dwarf rootstocks can be used to produce very small trees , which bear fruit earlier in their life cycle than full size trees. Dwarf rootstocks for apple trees can be traced as far back as 300 BC, to the area of Persia and Asia Minor. Alexander the Great sent samples of dwarf apple trees to Aristotle's Lyceum. Dwarf rootstocks became common by the 15th century, and later went through several cycles of popularity and decline throughout the world. The majority of the rootstocks used today to control size in apples were developed in England in the early 1900s. The East Malling Research Station conducted extensive research into rootstocks, and today their rootstocks are given an "M" prefix to designate their origin. Rootstocks marked with an "MM" prefix are Malling-series varieties later crossed with trees of the Northern Spy variety in Merton, England.

 

Apple trees are large if grown from seed, but small if grafted onto roots . There are more than 7,500 known cultivars of apples, resulting in a range of desired characteristics. Different cultivars are bred for various tastes and uses, including cooking, eating raw and cider production. Apples are generally propagated by grafting, although wild apples grow readily from seed. Trees and fruit are prone to a number of fungal, bacterial and pest problems, which can be controlled by a number of organic and non-organic means. In 2010, the fruit's genome was decoded as part of research on disease control and selective breeding in apple production.