What is a Rootstock?
The Bud 9 rootstock is an apple tree rootstock. A rootstock controls the tree’s size, precocity, cold hardiness, and partly its disease resistance (such as fireblight). 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.
Bud 9 Rootstock
This dwarf rootstock is resistant to collar rot and very cold hardy. Additionally, it’s about 15-25% smaller than M.9. However this depends on the cultivar and site you grow the trees on. Researchers bred Bud 9 rootstock (also known as Budagovsky 9 or B.9) in the former Soviet Union by crossing M.8 x Red Standard (Krasnij Standart).
A rootstock that grows well in one location, may not grow well in another. Therefore you must consider your specific site considerations before choosing a rootstock. When choosing a rootstock, some considerations for growers are
- how well the rootstock adapts to your soil
- the disease pressure on your site
- how well the rootstock anchors
- what size tree is optimal for your site
- precocity (bearing fruit at a younger age)
From our experience growing in New York, we have found the Budagovsky, Geneva, and EMLA series to be great options since they are virus free and produce very healthy trees.
Size of Tree
- While a rootstock does affect the size of the tree at maturity, the variety of apple, the soil type, the amount of sun and the way the tree is pruned will also have a significant impact on the ultimate height.
- For example, an apple tree on an M9 rootstock can grow to the same height as one grown on an MM106 rootstock with the appropriate care. However, the M9 tree will have fewer and thinner branches.
- Therefore, when you see below the height of the tree at maturity, it is an approximate maximum.