It affects tree size, vigour, pest & disease susceptibility, staking requirements and preferred soil type. We recommend giving rootstock choice some thought when selecting trees. Your choice may involve a trade-off between desired attributes, but with a better long term result for your orchard.
We offer four dwarfing rootstock options† to provide a good range of options for home gardeners and orchardists alike. The size of trees on each rootstock is expressed as a percentage of those grafted onto a seedling apple (seedlings of Granny Smith have been commonly used as rootstocks). This is a more reliable measure than a specific height as it takes account of variations in variety performance and local conditions which both influence ultimate size.
M.9 : Height* to around 33% of seedling tree (±1.8 metres), trees produce fruit within 2 years. Trees need staking or trellis support. M9 trees are susceptible to Woolly Aphid infestation. M9 is one of the most commonly used rootstock in commercial orchards in Australia and world wide. They are not ideal for organic production systems.
M.26 : Height* to around 40% of seedling tree (± 2.0 metres), early producer. M26 generally need staking unless sheltered from wind and are susceptible to Woolly Aphid infestation making them less suitable for organic production. They can produce vigorous suckers and are reported to be intolerant of extended wet soil conditions.
MM.102 : Height* to around 45% of seedling tree (± 2.4 metres), early producer, long term staking not required. Quite resistant to Woolly Aphid making them ideal for organic gardeners.
MM.106: Height* to around 50% of a seedling tree (± 2.7 metres), with moderate vigor and heavy cropping potential. Trees on MM.106 are well anchored, resistant to Woolly Aphid, adapt well to a wide range of soil types and climatic conditions, making it a very popular rootstock world wide.
Orange Pippin has collected some useful information on rootstocks, although not all is directly applicable to Australian conditions. For example we don’t have fireblight in this country – fortunately!
Each of our rootstock options can be espaliered with MM.102 and MM.106 being ideal for the purpose. M9 is suitable for a compact espalier, perhaps no more than 2 metres wide while M26 can be maintained at a wider size.
We recommend Alan Gilbert’s book Espalier for an excellent explanation of how to create espaliers using a wide range of plants including many types of fruit tree.
Big is not necessarily best!
Beginning in 1912 The East Malling Research Institute in England selected and began trials of a range of rootstock material. Clones ranged from those with a very dwarfing influence through to those with an invigorating influence on the cultivar. One of the interesting features of dwarfing rootstocks is that the dwarfing influence does not extend to the fruit. In fact fruit on younger trees is often larger.
The resulting Malling series, identified by the letter M followed by a number have gone on to play a major role in commercial apple growing throughout the world.
In 1928 work began on another equally important series of rootstocks when the East Malling Research Institute together with the John Innes Horticultural Institute began a program to produce woolly aphid resistant material, an attribute not found in the Malling selections. The resulting trees were named the Malling Merton series (denoted by MM and a number).
Some practical ‘modern’ benefits of clonal dwarfing rootstocks
Dwarf trees need less water in a dry climate, less fertiliser in a world of scarcity, take up less space in a smaller yard, have a lighter impact on surrounding plants, are easier to protect with netting, are safer to maintain and pick, produce more fruit per square metre (trials show nearly 50 tonne per ha is achievable, ie 5kg per square metre! And that is after only 2 years in the ground), produce fruit much quicker than seedling rootstocks and allow more varieties to be planted in a given space.
†We produce fewer M.9 and M.26 trees due to lower demand, but can graft any of our varieties onto these rootstocks to order.
*Plant growth is always influenced by climate, nutrition, water availability, etc,
so height figures are always only a guide.