It’s All In The Roots- Rootstocks For Fruit Trees

By Richard Flowers, ACCNP-Green Thumb Nursery-Ventura

Today, I would like make you aware of important considerations to take into account when selecting fruit trees like Apples, Apricots, Plums, Peaches, Nectarines, and Cherries. By implementing certain considerations your tree will thrive and become a semi-permanent fixture to your home landscape or orchard for many years to come.

There are four considerations to take into account:

1. The first consideration is to take into account is its adaptability to your soil and climate.
2. The second one to be aware of is the ability to resist certain damaging insects or diseases the plant may be susceptible to or prevalent in the area.
3. The next important item to be aware of is the age at which the tree may bear fruit.
4. The final consideration is how well the roots anchor the tree to the soil.

It all happens with the roots the plant is growing on. The rootstock may be called by many different names for the particular type of fruit. Plums, Peaches, Apricots, and Nectarines may all be grown on different rootstocks for different purposes. A rootstock is the bottom portion that extends into the ground from the graft and it is found just below the scion, the above portion. The graft is the union that fuses the scion and rootstock together and is usually above the ground (please see diagram). Growers and researchers have developed specific rootstocks for fruit trees so they can better thrive in adverse, troubling, and other situations that can weaken or kill the tree. The rootstock attributes and characteristics make the fruit tree more hardy, strong and thrive better in a given situation.

In many planting locations, it is critical to understand and become familiar with the rootstock because it is the most important part of a fruit tree. If a tree’s rootstock is not conducive to the conditions it is growing in, nothing else is likely to matter, that variety of Peach or Plum you are craving is of no value therefore the tree doesn’t thrive.

The number 1 reason people lose fruit trees is water-saturated soil. The remedies are: ensure adequate drainage, do not overwater, and plant wet-soil tolerant rootstocks.

Now let’s dive into the specifics of several rootstocks that have the ability for your tree to thrive in the landscape or orchard. Let’s start with Apples.

Do not be alarmed if your Apple has a smaller caliper stem (younger plant) and have very little or shy roots, this is normal and will do fine and thrive in your landscape or orchard.

M-111 for Apple:
If you are looking for an Apple that tolerates wet, dry or poor soil, and withstands drought then M-111 rootstock is the answer for you. This is the most common rootstock you will find because it is overall the strongest and resists woolly apple aphid (a serious insect that could kill young trees or weaken older trees), collar rot (a damaging phytopthora root rot disease), and bears fruit at young age (precocious). On M-111 for Apple the semi dwarf is unpruned tree height is 80-90% of standard, or about 15-25 ft. tall. Trees can reach a large size if not pruned. Trees on M-111 may be held to any desired height by summer pruning.

M-7 for Apple:
Another semi dwarf Apple rootstock to consider is M-7. This rootstock also induces early and heavy bearing but also has resistance to fireblight ( a debilitating disease that could cause death ). M-7 has resistance to powdery mildew( a fruit, branch, and foliage fungus that can reck havoc on the plant), and moderately resistant to collar rot. This rootstock provides good anchorage into the soil so the plant is stronger. M7 is also a good candidate for areas that have hard freezes during the winter and is widely adapted. However it is prone to suckering a lot and is not as common to find than M- 111.Trees may lean in rocky, shallow or steep soil where staking may be required, however it is free standing in deep, well drained soils. Trees can reach 12-18 feet tall if not pruned. M-7 may be held to any desired height by pruning in the summer.

Geneva®969 for Apple:
The final semi dwarf rootstock for Apples is Geneva®969. The hallmarks of this rootstock is that the precocity (bearing fruit at a young age) is better than M-7, resistant to woolly apple aphid, and is free standing. Geneva also produces minimal suckering and is resistant to crown gall. It is also a good choice for container growing if in ground planting is not an option.

Cherry Rootstocks:
It is critical that Cherries have exceptionally well drained soil. If you must plant in a clay or poorly drained soil be sure to plant on a mound for better air flow, drainage, and water penetration.

Maxma® 14:
If you had problems in the past with your Cherry not thriving because it is staying too wet especially in a clay soil then Maxma® 14 may be right for you because it has better tolerance to wet soils and also performs well in calcareous soils (but good drainage still can’t be over emphasized). Cherries are dwarfed to about 2/3 of standard (10- 12 feet tall), however less dwarfing may be expected in fertile, loamy soils. The Cherries will be well anchored into the soil making them a strong plant with very little suckering. And of course Maxma® 14 height can be pruned lower to suit your needs . Because Maxma® 14 produces a much smaller tree, do not be alarmed if your Cherry will have very little or shy roots, this is normal and will do fine and thrive in your garden or orchard.

Mazzard:
Mazzard is a Standard (full size) rootstock for sweet cherries that is vigorous and more tolerant of wet soils, (but good drainage is still a must), resistant to root-knot nematodes, and oak-root fungus. Mazzard is a popular Cherry Rootstock that usually has a husky and larger root system with good anchorage into the soil and is very adaptable. Please keep in mind Cherries on this rootstock are not precocious.

Peach, Plum & Hybrid Rootstocks:
Do not be alarmed if your Peach, Plum, or Nectarine on a smaller caliper stem( younger tree) have very little or shy on the roots, this is normal and will do fine and thrive in your home orchard or garden.

Citation:
For those of you who would love to have a Peach, Plum or Nectarine and your planting site has clay soil, doesn’t drain well, and is precocious, then look for the one labeled as Citation. Citation is dependable, takes off in the soil, and often times produces a large fruit size. Even though it is considered a semi dwarf rootstock, it still grows too large (15 feet tall) for smaller landscapes. Consider pruning it down to a size that best suits your needs.

Nemaguard:
Nemaguard is a standard (full size ) rootstock used for Nectarines, Plums, and Peaches. It is very vigorous, strong growing, supplies good anchorage, low suckering, precocious, and is ideal for a sandy soil. Not tolerant to water logged or clay soils. If you must plant in a clay soil be sure to plant it on a hill.This rootstock resists root-knot nematode but is prone to oak root fungus. Trees can reach a large size if not pruned to a size that is manageable to your needs.

Lovell:
Still some standard Peaches or Nectarines may be on a rootstock that can tolerate wetter soils than the previous one ( Nemaguard). Lovell tends to be very drought tolerant, exhibits good anchorage into the soil, tolerates very cold conditions, and is very dependable.Trees can reach a large size if not pruned.

Myrobalan 29C for Apricots and Plums:
Do not be alarmed if the chosen Plum or Apricot has a smaller caliper stem ( younger tree) and you experience very little or shy on the roots, this is normal and will do fine and thrive in your planting site

For those Apricot and Plum lovers who seek a plant that tolerates wet soil, is resistant to root knot nematodes, and has some resistance to oak root fungus then this is the way to go. Myrobalan 29C has a good tolerance to water logging, adaptable to medium to heavy soils, and provides good anchorage. Some suckering is possible. Even though the root system is shallow the tree will still be vigorous. Trees can be pruned to any desired height by pruning.

I hope you find this information useful as an aide to your fruit tree selections at your favorite Green Thumb Nursery. If you have any questions or need help selecting a fruit tree for a given area please reach out to us.

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