Selecting Rootstocks and Apple Cultivars
Primary grower considerations when choosing any plant material for a Montana orchard is whether or not the roostock and/or cultivar is cold hardy enough for your region. Growers should be familiar with their USDA Plant Hardiness Zone and should use this information to determine which rootstocks and cultivars will be appropriate for their location. Secondary to cold hardiness, growers should select rootstocks and cultivars that fit with their overall orchard design and management strategy, are marketable to the surrounding community, and demonstrate some resistance to common Montana diseases such as fire blight and scab. The following information will help growers decide which rootstocks and cultivars to select for their orchards and where to source these materials.
Rootstocks influence the size, vigor, and percocity (ability to induce fruiting) of the scion they are grafted to. In addition, they have been bred for disease resistence and have varying levels of cold tolerance. In Montana, the order in of priority for selecting rootstock should be 1) cold hardiness, 2) desired orchard design, and 3) resistence to fire blight. The latter is particularly true for those interested in growing apple cultivars that are highly susceptible to fire blight, as a tolerant or resistant rootstock will survive severe fire blight damage and can be regrafted with a new cultivar if need be. Several cider cultivars grown in Montana have been reported to be susceptible to fire blight by growers, so a fire-blight resistant rootstock is an important asset for Montana orchardists.
Many growers interested in dwarfing trees for modern orchard systems have found success with M26, Bud 9, and the relatively new line of Geneva rootstocks, namely G41 and G935, which are reported to be cold hardy and resistant to replant disease and fire blight. Rootstocks that result in larger trees and have demonstrated good cold hardiness in Montana include M111, Bud118, and seedling rootstock. These rootstocks and several others are compared in this chart which was compiled through NC-140, a group of rootstock researchers across North America, including researchers from Washington, Colorado, Idaho and Utah. At WARC, we currently do not have our own research-based information to provide on rootstocks, however we are establishing a cider apple training system trial using G935 and EMLA106 rootstocks.
Montana isn't just ideal for McIntosh apples. There is a large selection of popular apple cultivars that can be grown successfully in Montana, including Honey Crisp, Gala, Ginger Gold, Ida Red, Sweet Sixteen, Fameuse, and several other heritage varieties that pay homage to our pioneer past. This list of cultivars grown in Montana provides a starting point for growers to explore options that have been successfully grown in the state. Descriptions of these apples can be found by searching www.orangepippin.com. For growers east of the divide, the Montana Heritage Orchard Program has included several research sites around the state that include cold hardy apple cultivars. Preliminary results from this research can be found on the WARC Research Site.
For growers interested in cider apple production, the list of cider apples planted in the Rocky Mountain West is long, but not reliable for information on what will do well in our cold, dry climate. Many plantings are young and while research is currently under way to explore which cultivars can withstand our cold temperatures and threats from fire blight, the results of this work are not yet available. The Performance of Cider Apple Cultivars in the Rocky Mountain West does provide a summary of grower experiences from across the region for the top 20 cultivars planted.
When selecting cider apple cultivars, growers should focus on proven cold hardiness and be aware of the tendency for these trees to be susceptible to fire blight. Growers must protect them from fireblight early on with a preventative spray program and aggressive pruning if infection does occur. Attention should also be paid to bloom and ripening times. A good rule of thumb for selecting trees with reliable yields is to choose cultivars with bloom and ripening times similar to cultivars proven to succeed in Montana like McIntosh, Wealthy, and Honey Crisp.
WSU is currently a leading resource for information on cider apple cultivar performance, though this is focused on research conducted west of the Cascades at the Mt. Vernon research station. Much of the information located on WSU's Cider website, however, will be useful to any cider apple grower in the region. University of Saskatchewan has also conducted research into juice quality and fire blight susceptibility of cold hardy apples that hold potential for making hard cider. A summary of this work is available in the Agriculture Development Fund (PDF).
None of these lists is inclusive of the large range of apple cultivars that can potentially or have proven to grow successfully in Montana, but they serve as a good starting point for growers to explore the possibilities for their own orchard.
Sourcing Plant Material
While many dessert cultivars will be available in smaller quantities through local nurseries, for larger purchases and wider selection, particularly for cider apple varieties, growers will need to order trees from out-of-state nurseries. These sources should be vetted for providing disease and virus free plant materials and offering some level of guarantee on the plant material they sell. The Clean Plant Center Northwest keeps a list of certified nurseries in the northwest and can also be a good source of plant material themselves.
The desired size and age of the tree will depend on the growers intent. Growers planting high-density systems with the goal of early production will need to purchase feathered trees with a minimum caliper of 5/8". For growers who are less concerned with financial gains and early production, whips and smaller caliper (<5/8") trees will be a less expensive option, though these cost savings will often level out due to slower production and lower yields over the long-term.
For dessert apple cultivars, several Montana nurseries carry cultivars that will do well for backyard growers in Montana. Several nurseries out of Washington — including C&O, Van Well, and Willow Drive — offer a broad selection of cultivars and rootstock options, as well. WSU keeps a comprehensive list of nurseries that offer cider apple cultivars. For specific combinations of cultivars and rootstocks, growers will need to make custom orders which requires some forethought, as these will take at least two years to fulfill. General costs for trees will depend greatly on the cultivar, age, and quantity purchased. For dessert apples, this cost tends to range from $2.50 to $12 per tree, whereas cider apples will cost quite a bit more, ranging from $10 to $25 per tree.