When it comes to apple orchards, many consumers have a picture in their heads of Johnny Appleseed planting apple seeds all over the place. We should be very glad that’s not the case in reality, though, as aside from the nostalgic imagery, the way orchards are actually propagated is vastly superior. And the “root” of modern apple production is, well, rootstock!
To understand why rootstocks are so important to apple production, it helps to first understand how apples are pollinated, and luckily, we just posted a brand new infographic on that very topic. For a typical apple blossom to grow into a high-quality piece of fruit, it needs to be fertilized by another blossom’s pollen. Adequate pollination is very important, so farmers usually bring in thousands of bees in the spring and often plant plenty of crabapple trees that produce terrible fruit, but lots of pollen.
Because blossoms are pollinated by other varieties, the seeds in the mature fruit contain genetic information from both the host and the donor pollen. So, if you were to plant the seeds from your Gala apple, you wouldn’t get a tree that produces identical Galas. Instead, you’d get a tree that may have a mix of Gala and crabapple characteristics – and even then, you couldn’t predict which characteristics you’d get from each!
To achieve the reliable growing and fruit characteristics of your favorite variety grafting is required. This way, you get an exact “copy” of the cultivar orchardist wants to grow.
There are multiple ways to graft apple trees, but it is essential to obtain disease free scion wood from trees of the desired variety. The scion must then be cut in a complementary manner to the rootstock that it will be grafted onto. The scion and rootstock are then combined with their cambium tissue touching (the “growing” part of the tree, located between the wood and bark) and bound together.
Rootstock selection is just as important as variety selection. While scions deliver the desired variety, each can be combined with a wide range of rootstocks with various characteristics, such as adaptability to specific growing conditions, resistance to certain diseases or insects, and compatibility with different scions.
Rootstock selection also allows growers to determine the eventual size of the tree. This allows growers to manage the planting distance between trees so the orchard can be worked according to their desired growing practices. Things like pruning, pest control and harvesting practices are all taken into consideration when determining rootstock selection.
In short, without the use of grafting and rootstocks, we would not be able to achieve genetically consistent apples or produce them nearly as efficiently as we do!