Dwarfing cherry rootstocks promote smaller trees, boosting cultural efficiencies
By Renee Stern
Bigger isn't always better.
With cherries, a dwarfing or semi-dwarfing rootstock offers orchard efficiencies that pay off while still producing desirably large fruit. What's more, some variety selections known for their problems turn into winners when paired with dwarfing rootstocks.
"To me, it's a no-brainer," says Matt Whiting, assistant horticulturist at Washington State University's Irrigated Agriculture Research and Extension Center in Prosser. "The advantages have been demonstrated clearly."
Dwarfing rootstocks are more precocious, reaching production levels in three or four years rather than the five or six years needed with standard rootstocks such as Mazzard and Mahaleb, says Lynn Long, Oregon State University's Wasco County Extension horticulturist.
Workers accomplish orchard chores--thinning, pruning and harvesting--more easily with smaller trees that don't require extensive ladder time, Whiting says. That's a key factor in a crop where labor accounts for 40 percent to 50 percent of production costs.
Long's harvest comparisons show workers picking 100 pounds per hour in a traditional Mazzard orchard and 170 pounds per hour in a "pedestrian" orchard planted on dwarfing Gisela rootstocks.
"Pickers love (smaller trees) because they can make more money," he says. And that pays off for growers not only by reducing labor needs but also making their operation more attractive when competing for workers.
Those productivity gains help recover planting expenses in almost half the time--typically 15 years with a standard rootstock compared to eight years on a precocious dwarfing rootstock, Long says.
Standard rootstocks tend to be "overly vigorous," leading to a greater percentage of shaded leaves that aren't earning back their growth costs to the tree, Whiting says. Dwarfing rootstocks offer better light distribution through the canopy to bring the system into more efficient balance.
A too-dense canopy also creates obstacles for optimal spray penetration, he says. A more balanced canopy, in comparison, eases pest and disease control.
Match rootstock to variety
But market preferences push cherry growers toward the largest fruit possible to maximize profits, holding many back from switching to dwarfing rootstocks. Smaller trees have a smaller leaf area to support the fruit.