Dec 26, 2018
Researchers refine growing techniques for Cosmic Crisp trees

Washington state researchers are refining their suggested best practices for growing Cosmic Crisp apples.

Apples from the WA 38 cultivar – a copyrighted cross of Enterprise and Honeycrisp – will be sold under the Cosmic Crisp brand name.

Only Washington state growers have access to the cultivar. Roughly 6.8 million of the trees have been planted to date with an additional 5 million plantings anticipated in 2019, according to Katheryn Grandy of Proprietary Variety Management (PVM).

Current plantings are about 5,800 acres.

The first Cosmic Crisp apples are expected for commercial release in 2019, and while the tree plantings are well on their way to roll out on schedule, researchers and Extension agents are helping growers navigate the details of cultivation on the way to that harvest.

“There is a lot of effort from the WSU Extension team to actually show growers how to best plant the trees and train them in the first couple of years,” said Ines Hanrahan, executive director of the Washington Tree Fruit Research Commission. “Research and Extension are focused on basic things, on how to best grow the tree. There is other research going into figuring out and honing in on the harvest window and also the maturity standards, to have those very uniform across the industry.”

The apples redden early but mature later on in the season. Photos: Stephen Kloosterman


Washington State University (WSU) Extension Tree Fruit Specialist Karen Lewis is responsible for an experimental one-acre block of Cosmic Crisp in Prosser. A twin one-acre plot is in Wenatchee, and the two plots are used to test growing practices.

In an early October day, Lewis gave a tour of the block in Prosser. She said she was a little disappointed by the number of apples on the tree.

“Money is earned or lost in cropload,” she said. She blamed the trouble on pollination, something the group is still experimenting with.

Washington State University Extension Tree Fruit Specialist Karen Lewis shows off a Cosmic Crisp apple.

“You choose your pollinators based on bloom time,” she said. Based on the timing, the group had earlier planted Granny Smiths in the block as pollinators. Now, the recommendation is Snowdrift and Mt. Everest crabapple trees.

Pruning/growth regulation WSU professor Stefano Musacchi has been researching the best ways to prune WA 38 trees.

“He looked at click pruning, which is tipping one-year-old wood, and he looked at bending,” Lewis said. “Over multiple years of studies, he has concluded that this tree best responds to click pruning. Going forward, I think that’s what most producers will be looking at.”

“The other thing we’re noticing in the acreage that’s been planted, a lot of interest in the bi-axis system,” she said.

“That’s to manage the vigor. The vigor in this variety needs to be managed, and one way to manage that is by developing a bi-axis system, to split up that vigor and create a calm and uniform block, which is the goal of any block, any variety, any grower anywhere.”

Lewis has also tried using the plant growth regulator, Apogee, to manage vigor.

“I would say that it’s worked well,” she said.

Cosmic Crisp apples also seem to brown slower than some other varieties.

Harvest and storage

Cosmic Crisp reddens earlier than it should be picked, so growers will need to carefully choose the right time for harvest.

“The main thing for a grower is to wait until it is mature, and not let the color fool you,” Hanrahan said. “It matures slowly on the tree.”

But there’s good news for the harvest: Cosmic Crisp has a long, two-week harvest window. And Hanrahan said there is not much variation between fruit on a tree and it may be possible to pick some blocks in a single sweep.

After Cosmic Crisp requires some time for the sugars and acids to balance out. Hanrahan said. PVM’s grading committee might possibly set a “do not sell until” date for Cosmic Crisp apples to ensure fruit hitting the market is of excellent quality.

Cosmic Crisp can be stored for up to a year “no problem,” she said, but needs a certain amount of time of storage for best taste.

“A Gala tastes really good if you take it off the tree and bite into it,” Hanrahan said, “Cosmic Crisp – it’s not that it tastes horrible, but it tastes better once you have it picked and put into storage for a few weeks. You wouldn’t want to sell it right off the tree.”

But the final taste is worth the wait.

“It’s very juicy and it has a very good texture,” Hanrahan said. “For me, what stands out is what a good shelf life it has. You can have it sit at room temperature for quite a few weeks and still have an excellent piece of fruit.”

– Stephen Kloosterman, FGN Associate Editor


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