How to Choose the Right Sweet Cherry Training System
Whenever I give Extension presentations on training systems, hold Michigan State University (MSU) research field days, or participate in orchard workshops around the world, I often get asked “Of all the new cherry training systems, which is the best?”
I’ve tried to always answer that there is not one single training system that is the absolute best choice for every grower. When each grower (and/or orchard manager) really understands the nuances of the training system in their orchard environment, that will be the best system for them as they develop an inherent feel for optimizing their trees’ performance. This is also why it can be difficult, and sometimes unwise, to switch from one system to another without a strong purpose in mind.
Every training system begins with good horticultural ideas and physiological concepts, but these can be misunderstood or forgotten as the orchard develops in unanticipated ways, since very few orchards respond exactly the same under the influence of different soils, climates, varieties, rootstocks, pest pressures, irrigation/fertility regimes, and labor forces.
I have seen great successes with nearly every cherry training system around the world, as well as disheartening train wrecks with nearly every system. Given a high-risk, high-reward fruit crop like sweet cherries, there are no training system “recipes” that come with guaranteed optimized outcomes.
Customer Is Always Right
While it is easy to say that every grower’s objective is to produce the highest yield of premium quality fruit at the lowest input cost, the reality is that different growers have subtly different production objectives that clearly influence their “best” choice of training system. Knowing the requirements of the primary targeted market ― and thus the anticipated all-important return price per pound ― is always paramount: specialty market, wholesale export shipping, wholesale domestic shipping, wholesale to local grocers, retail farm market, or pick-your-own? Customer expectations will influence cultivar choice and target fruit size, which in turn influences rootstock, training system choice, and target yields.
Anticipated availability and skill level of orchard labor further influences these choices. Available capital for high density vs. modest density tree plantings, free-standing vs. trellised or covered orchards, and non-precocious vs. precocious rootstocks all influence training system decisions.
For example, Kym Green Bush (KGB) orchards require much less capital and skill to establish compared to Upright Fruiting Offshoots (UFO) orchards, but over the life of the orchard, the UFO trees will be more conducive to partial mechanization for pruning and more efficient for labor to pick. Both of those orchard systems require fewer in-orchard decisions and are easier to pick than Tall Spindle Axe (TSA) orchards, but many growers and orchard workers have years of experience making appropriate decisions for spindle-type trees (see Fig. 1). In such operations, change is unlikely to succeed unless there is significant pressure to do so, such as changes in labor availability or skill.
Economics Should Dictate
More than one grower has contacted me as they struggled with making a decision on purchasing readily available nursery trees on Mazzard or Colt rootstocks or ordering the same varieties on Gisela rootstocks for delivery two years down the road. In most cases, I would tend to recommend the Gisela rootstocks, since their precocity means that even with a two-year delay in planting, they may begin producing about the same time as an earlier-planted Mazzard orchard. However, even here there are exceptions.
Mazzard or Colt may be a more logical choice in very hot climates, or with non-precocious training systems like KGB, or with very precocious varieties like ‘Sweetheart.’ Conversely, such vigorous non-precocious rootstocks, and even vigorous precocious rootstocks like Gisela 6 or 12, may be a disaster for Super Slender Axe (SSA)-trained orchards. That is, unless the SSA orchard site is rocky or otherwise of poor fertility and water-holding capacity, in which case the more typical decision of dwarfing Gisela 3 or 5 might be a disaster due to insufficient vigor.
A visiting scientist in my laboratory recently returned from a quick trip to the Pacific Northwest (PNW). He remarked not only on the incredibly innovative commercial orchard systems he saw there (see Fig. 2), but also that he was even more surprised to see that the apparent majority of the sweet cherry orchards ― at least along the major fruit-growing highway corridors ― are larger, older trees in moderate to low density plantings (see Fig. 3).
I noted that even old orchards of large trees with the right varieties in a great growing climate like the PNW can yield high-quality fruit that bring good returns in current markets with current labor availability in the western U.S., but as labor becomes more expensive and less available, such inefficient orchards will quickly shift from profitable to obsolete.
Economics will drive the adoption, and further advancement, of innovative orchard systems. All growers expecting to remain in the production game long-term should be conducting their own small-scale experiments with training systems, new rootstocks, and new varieties in a corner of their operation to gain the localized experience and inherent feel for how to adapt their orchards to the ever more rapid pace of today’s technological advances, changing climatic extremes, and potential political impacts on markets, labor, and energy.