The science of growing a better apple
An increasing number of modern apple farms more closely resemble vineyards in the size and layout of their trees.
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It was almost certainly an apocryphal apple.
But the legend that a piece of pomaceous fruit fell from a malus domestica tree on to Isaac Newton’s head — jarring the Law of Universal Gravitation out of his noble noggin — is the most famous in all of physics.
So, if you’re out picking your own McIntosh, Red Delicious or Royal Gala at an Ontario orchard this fall, your thoughts might reasonably wander to science. And the science behind the ancient art of apple growing is becoming increasingly modern and sophisticated.
Photos: Apple varieties grown in Ontario
“You can do a lot of things with apples,” says John Cline, an expert on the fruit at the University of Guelph. “There’s a lot of technology, a lot of knowledge for sure. There’s always something new going on.”
New brands of apples — yet to be named — are currently being cultivated among the thousands of seedling trees being grown at the federal government’s apple research complex in Summerland, B.C., Cline says.
And genomic research is being conducted in Ontario and elsewhere that will make breeding more certain and trees more disease and pest resistant.
But the fact you’ll likely be plucking high-hanging apples while standing on the ground during your family’s afternoon picking expedition — and it’s a bumper crop in the province this autumn — points to the biggest and most pervasive shift in apple horticulture over the past two decades.
The apple tree that might have shaded Newton’s deliberations would have been more than seven metres high and borne hundreds of apples each autumn, Cline says.
Like the trees you might have climbed and raided as a kid.
But an increasing number of modern farms more closely resemble vineyards in the size and layout of their trees, even down to the wire-supported plant rows.
In nature, apple trees, which are hardwoods, would devote their first five or six years to growing a sturdy base and branches before donning spring blossoms and bearing their heavy fall fruit, Cline says.
And those juvenile trees would grow for decades, often sprouting swings and hammocks in their maturity.
But it would be hard to string a hammock, let alone a swing, from an apple tree in a modern orchard. The stunted size — a maximum two to three metres with spindly trunks — is the result of a century-old technology that has taken root across North America since the 1980s and been perfected over the past 10 to 15 years. It’s known as the dwarfing rootstock system and the vast majority of apple farms across the continent are now employing it to transform their orchards into more efficient and productive operations.
As the name implies, the trick to growing smaller trees is in the specialized dwarfing roots now widely available to farmers.
The roots — there are a number of varieties — were bred and refined at international agricultural labs, including those at the University of Guelph and are designed to make trees grow quickly. And grow small.
And they can play host to any variety of apple, simply by grafting the buds of the desired type on to the dwarfing root.
Leslie Huffman, an apple expert with the Ontario Ministry of Agriculture and Food, explains the process: “This past spring, if I was a nursery man, I would have planted a stick that had roots on it that (were a dwarfing variety), and I’d put it in a row.”
Then in August, she says, the nursery would collect bud-bearing twigs from the desired varieties of apple trees and graft them on to the planted roots.
This is done by cutting similar-shaped chips from the bark of the root and bud sticks, lining the cuts up and tying together the two tree parts with tape. The following spring, the two living sticks would have healed into one, with the bottom part being dwarfing root stock and the top being the intended type of apple.
From then on, Huffman says, the root takes control of the rate and size of the tree’s growth while the grafted bud decides the fruit it will produce.
Introduced into Canadian commercial operations in the late 1970s, the dwarfing rootstocks have been significantly refined over the decades. “There’s been a slow progression from medium sized to smaller sized, from what we call semi-dwarfing to very dwarfing,” Cline says. “And the biggest changes have been in the last 10 or 15 years.”
Modern rootstocks can cut the time it takes a tree to produce fruit down from six years to two after shipment from a nursery, and also coax bigger apples out of the plant. And everybody wants and is willing to pay for big fruit.
As well, the newer rootstocks can offer the above-ground tree — or scion — better disease and cold resistance, Cline says.
Most importantly, however, it makes the labour-intensive tending of those trees — the constant pruning, the fall picking — much less arduous and costly, says apple farmer Scott Lunau.
(Huffman says labour can represent 30 to 50 per cent of an orchard’s production costs and that the smaller trees are far easier to work.)
“You can spend most of your time working from the ground or from short platforms,” says Lunau, who owns Albion Orchards, a 6,500-tree operation in Caledon. “And if you do need a ladder, you move it a couple of times instead of dragging it all around a big tree.”
But Lunau, who has been replacing his standard trees with dwarfing stock growth over the past 12 years, says many of the smaller plants would not support a ladder.
Indeed, as in vineyards, the trees often need to be supported with stake and wire trellises.
“Without support they would just fall over in the wind. They would just snap off and break because of the crop load.”
The smaller trees, of course, yield less fruit — perhaps 75 to 200 apples a season versus 1,000 or more on a natural tree, says Cline.
But, he says, their size allows growers to plant far more of them. And the pruning ease and sparser branches allow more sunlight in to maximize apple development.
“Some growers are planting 3,000 trees per acre, whereas in the past there might have been a couple of hundred trees per acre,” Lunau says.
Lunau says the fast-growing smaller trees also allow large farming operations to adjust their orchards more easily to shifting consumer tastes in apples.
“A lot of them, when the trees are 10 or 12 years old, they just rip them out, they rip them out and start over again planting tens of thousands,” he says.
New apple brands
At the non-profit Vineland Research and Innovation Centre west of St. Catharines, for example, scientists are using DNA screening to help ease the arduous breeding process traditionally used to produce new apple brands.
(Huffman says that some new brands are simply “found,” having been produced by nature’s pollinating whims.)
Daryl Somers, director of applied genomics at the Vineland centre, says operations like the federal Summerland research nursery work to create new apples by selectively breeding existing brands together in a hit-and-miss attempt to find good-tasting progeny.
These breeding programs, however, can take 15 years to produce marketable new apple varieties and can go through thousands of “crappy-tasting” fruit trees in the process.
So since 2009, Somers team has turned to DNA analysis to help streamline that process.
Simply put, the Vineland researchers are seeking DNA fingerprints of new trees that focus groups and experts have determined are producing flavourful fruit.
And instead of breeding these tasty trees randomly with a host of others, they will seek out only those sapling plants that have matching DNA profiles for planting and cross-pollination.
“You can rate what a person’s perception of an apple is and relate that to an actual DNA sequence,” Somers says. “The trick is, you want to avoid the trial and error. You want to only be (planting) apples at that early stage that have a chance to produce a good-tasting apple.”
How did your your garden grow this year?
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