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 onto which they are grafted. In addition, they have been bred for disease resistence and have varying levels of cold tolerance. In Montana, we recommend the following order of priority for selecting rootstock: 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 needed. 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 rootstocks 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 from Washington, Colorado, Idaho and Utah. Montana does not currently have its own research-based information to provide on rootstocks; however, WARC is establishing a cider apple training system trial using G935 and EMLA106 rootstocks.
There is a large selection of popular apple cultivars that can be grown successfully in Montana, including Honey Crisp, Gala, Ginger Gold, Ida Red, McIntosh, Sweet Sixteen, Fameuse, and several other heritage varieties that pay homage to our pioneer past. See this list of cultivars grown in Montana. Descriptions of these varieties 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. See our comprehensive list of apple cultivars recommended for Montana.
There is a lengthy list of cider apples planted in the Rocky Mountain West, but only a subset of cultivars will thrive in our climate conditions. Many of the plantings are young, and while research is currently underway 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 provides a summary of grower experiences from across the region for the top 20 cultivars planted.
When selecting cider apple cultivars, growers can focus on proven cold hardiness and be aware of the tendency for these trees to be susceptible to fire blight. Youn trees should be protected from fire blight with a preventative spray program and—if infection occurs—aggressive pruning of diseased limbs. For a reliably-yielding crop, choose cultivars with bloom and ripening times similar to cultivars proven to succeed in Montana like McIntosh, Wealthy, and Honeycrisp.
Washington State University is a leading resource for information on cider apple cultivar performance, although their research site is west of the Cascades at the Mt. Vernon research station. However, the information on WSU's cider website will be useful to any cider apple grower in the region. University of Saskatchewan has also conducted research on 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 have potential or have been proven to grow successfully in Montana, but they serve as a good starting point for growers to explore possibilities.
Sourcing Plant Material
While many dessert cultivars are available in smaller quantities through local nurseries, for larger purchases and wider selection—particularly for cider apple varieties—commercial 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 a guarantee on the plant material they sell. The Clean Plant Center Northwest keeps a list of certified nurseries in the northwest and can itself be a good source of plant material.
The desired size and age of nursery stock will depend on the grower's intent. High-density systems with the goal of early production will do best starting with feathered trees (ones with branches) 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 less expensive. However, cost savings will often neutralize due to slower production and lower yields over the long-term.
Several Montana nurseries carry dessert apple cultivars that will do well for backyard growers. Washington state nurseries—including C&O, Van Well, and Willow Drive—also offer a broad selection of cultivars and rootstock options. WSU maintains 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. Cider apples will cost quite a bit more, ranging from $10 to $25 per tree.