Crop management of sweet cherries starts even before trees are planted. Matching productive characteristics of variety to
the vigor of the rootstock and using appropriate training systems will help eliminate size and yield problems.
Planting a new cherry orchard today, with so many new variety and rootstock choices, is more complex than a decade ago, says Lynn Long, Oregon State University Extension educator for Wasco County.
“It’s not as simple as it was,” he said. “You don’t just order Bing on Mazzard anymore. Rootstocks and training systems that worked well for Bing may not be appropriate for other varieties.”
Growers must consider the productivity of the variety and match it to the vigor of the rootstock and training system, Long said, adding that there are also several training systems to choose from.
“You want to avoid the two extremes,” he said, adding that Sweetheart on a Gisela 6 trained to a central leader “would be a difficult combination.”
For example, the large cherry variety of Regina is known to be low or nonproductive, while Chelan, Lapins, and Sweetheart are categorized as productive. Long explained that putting the nonproductive Regina or Tieton on a productive rootstock like Gisela can result in large fruit with good yields.
In a fifth-leaf trial of Regina on G.5, G.6, and G.12, average yields were 4.4 tons per acre, 8.2 tons, and 7.0 tons, respectively. Sixty-two percent of the fruit was 9.5 row or larger. He noted that the trees on G.5 were planted to an 8 feet by 16 feet spacing and would have yielded more if they were planted like the others at 10 feet by 16 feet.
A research trial at the OSU experiment station with Bing, classified as an intermediate producer, on Mazzard, G.5, G.6, and G.12 resulted with nearly half of the fruit graded 10-row or larger. Similar results were observed from a trial at Mel Omeg’s, an orchardist at The Dalles, Oregon.
“So the question is, why would you plant an intermediate variety on a Gisela rootstock if you can get the same fruit size from a Mazzard rootstock?” asked Long. “Why should we be looking at higher-density, pedestrian orchards? Because we can save labor in picking and pruning costs, and because of return on investment.”
Research shows that the average worker picks 100 pounds of fruit per hour when using a tall ladder, according to Long. In a pedestrian orchard, the average worker can pick 171 pounds per hour.
Agricultural economist Clark Seavert of Oregon State University has compared the return on investment from a Bing on Mazzard rootstock cherry orchard spaced at 8 by 15 feet to a precocious, high-density Gisela rootstock orchard spaced at 10 feet by 16 feet.
He found that the high-density Gisela orchard took 8 years to recoup investment costs, compared to 15 years on the standard density Mazzard planting.
Long is also studying different training systems to evaluate which works best on the different rootstocks. In a trial of fourth-leaf Sweetheart grafted on G.6 and Mazzard rootstocks, he is comparing the Vogel spindle or central leader, open vase, and Spanish bush training systems. Data collected shows that the central leader on G.6 yielded more than 63 pounds of fruit per tree, nearly twice that of the open vase, and produced the largest fruit.
“When you have a productive rootstock like G.5, you want a system that reduces crop load, such as the Spanish bush,” he said. “If you’re on Mazzard, you need to find a training system that increases crop load, like the central leader or palmette system.”
For the nonproductive varieties of Regina and Tieton, productive rootstocks like G.5, G.6, and G.12 would be good choices, Long said. Productive training systems—central leader—should be used.
Orchardists will have more training system choices when using intermediate productive varieties, he added.
For intermediate varieties, either productive or non-productive rootstock, Mazzard or G.5, G.6, or G.12, are suitable choices. Training system choices are the steep leader, central leader, or Spanish bush. Rootstock choices for productive varieties would be ones that are nonproductive, such as Mazzard. Long noted that appropriate training system choices would be the steep leader or Spanish bush.