How should I choose among dwarfing rootstocks for my apple orchard?

Choosing the best dwarfing rootstock for your orchard will depend on multiple factors. Probably one of the most important is the cultivar that will be propagated on the rootstock. Cultivars vary greatly in vigor, with some being very weak growing (‘Honeycrisp’) compared to others that are very vigorous (‘Cripps Pink’/’Pink Lady’). You should select the cultivar/rootstock combination that will give you the desired tree size for your desired tree density, support system, soil, and management system.

The disease sensitivity of …

How do rootstocks affect apple fruit size?

Results from a number of apple rootstock trials in different regions of North America indicate that some rootstocks can influence fruit size. Trees on M.7, G.16, and M.26 generally produce smaller fruit than trees on M.9. Most other tested rootstocks produce fruit slightly smaller than M.9. Although experiments have not been performed to compare fruit size from trees grown on semi-dwarf or non-dwarfing rootstocks, orchard observations indicate that fruit produced by trees on M.9 are larger than fruit produced by …

What is white root rot in apple trees?

White root rot, caused by the fungus Scytinostroma galactinum (formerly Corticium galactinum), has been known as a parasite of apple trees for many years and is widely distributed (Canada to Texas and westward to the Pacific Coast, Europe, West Indies, and Japan). It is found in both bearing and non-bearing apple orchards. Other hosts include a wide variety of woody plants, ornamental shrubs, and herbaceous perennials, including white pine, ash, peach, blackberry, dewberry, Japanese wineberry, dogwood, sumac, white campion, …

How do I identify and manage Armillaria root rot, or shoestring rot, in apple?

Armillaria root rot, also known as shoestring root rot, is a soilborne disease that can affect several fruit crops, but it is most common in the eastern United States on peach and apple trees. Its host range also includes numerous species of deciduous and evergreen trees, shrubs, and woody vines. The greatest prevalence of the disease is in orchards planted on newly cleared land in which the soils are sandy and well drained. In these locations, pieces of wood invaded …

What is black root rot (dead man’s fingers), and how do I identify and manage the disease?

Black root rot, also called dead man’s fingers or Xylaria root rot, is occasionally observed on mature apple and cherry trees. Although trees of all ages can be infected, most trees that die from black root rot are at least 10 years old. Black root rot is caused by two species of the fungus Xylaria, X. mail and X. polymorpha, with the former being more common in the southern Appalachian states, and the latter more common in the eastern …

How do I determine the spacing between trees on a given rootstock for my apple orchard?

Determining the correct spacing for a rootstock/variety combination in a particular orchard is worth a lot of pre-planting thought and effort. Trees that are planted too close together for their vigor will be a struggle to maintain during every year for the life of the planting. Additionally, the amount and quality of fruit production will decline when inadequate light is available throughout the tree. On the other hand, trees that don’t have enough vigor to fill their spacing will result …

Are there restrictions to grafting my own apple trees?

Some cultivars of apple are under patent. If the patent is still applicable, then you must contact the nursery (or whoever holds the patent) and pay the royalty for each tree you propagate. Failure to do so could lead to criminal penalties, a monetary judgment (and/or fine), and destruction of the trees you propagated. Apple cultivars that are part of an exclusive club or licensing agreement are also illegal to propagate, and there usually is no avenue for a “non-club …

Which rootstocks are winter hardy?

Rootstocks can affect the development of cold hardiness in apple trees, but this is a complex trait, and it may depend on what time of the winter with which one is concerned. Some rootstocks, such as Robusta 5, can cause a tree to harden early in the winter, and these trees are very cold tolerant during the early winter. Some rootstocks, such as Robusta 5, that induce early cold hardiness also lose their hardiness early in the winter in response …

What experimental rootstocks for apples are being looked at in the U.S.?

Many apple rootstocks are being evaluated for potential use in the United States by the NC-140 Multi-State Research Committee. These rootstocks have come from breeding programs in the United States (CG, G), Great Britain (M), Germany (PiAu and Supporter), Poland (P), Czech Republic (J-TE), Japan (JM), and Russia (B). Specific rootstocks that are currently under evaluation in NC-140 plantings include the following: B.9, B.10, B.7-3-150, B.7-20-21, B.67-5-32, B.64-194, B.70-6-8, B.70-20-20, B.71-7-22, G.11, G.16, G.41, G.202, G.935, CG.2034, CG.3001, CG.4003, …

How do nurseries grow rootstocks?

Rootstocks are commonly propagated by layering to form large stool beds. The “mother plant” is set out in the field. The plant may either be mounded, or it may be trench layered. In mounding, the plant is cut off close to the ground. As the new shoots emerge from the mother plant, they are partially covered with soil or well-decomposed sawdust. The sawdust is renewed periodically during the growing season to prevent the base of the shoot from exposure to …