What is a rootstock? A fruit tree’s rootstock controls primarily the tree’s size, precocity (how early the tree bears fruit), cold hardiness, and partly its disease resistance (such as fire blight). In order to grow a reliable and high quality fruit tree, growers graft the scion, which is above the ground and responsible for the fruit’s characteristics and disease resistance, onto the rootstock, which is underground. Grafting is a horticultural technique growers use to combine the tissues of two plants so that they continue to grow together with certain desired characteristics.
Rootstocks control the tree’s size. Therefore when the tree is fully mature, it can range from being dwarf (6-8′) to standard (20-30’+). However with proper pruning, you can also control trees on semi-dwarfing or semi-standard rootstock to grow to a smaller size.
What is precocity? Precocity measures how early the tree will start to bear fruit from the time the tree is planted. Dwarf rootstocks are usually more precocious than semi-dwarf or standard rootstocks, which means they will bear fruit earlier. However the fruit cultivar can also influence the precocity of the tree. For example the Northern Spy apple tree usually bears fruit late compared to other apple trees such as Honeycrisp.
Rootstocks can also control the tree’s cold hardiness, or the tree’s ability to tolerate cold temperatures. For example, the Budagovsky series, which was developed in the Soviet Union, is very cold hardy.
Rootstocks can also be resistant to diseases such as fire blight, collar rot, and woolly apple aphids. Many of the rootstocks that researchers have developed in the 20th century, such as the Geneva series for apples and OHxF series for pears, are made to be resistant to common diseases and viruses.
Interested in growing trees? Discover more about trees in our guides or search our fruit trees.