We Might Be Able To Save Apples From Climate Change By Getting Them To Bloom Later

As the climate continues to warm and causes weather to become more unpredictable, researchers in Michigan are on a mission to make apple trees more resilient—and the trick may be to get them to bloom later.
For example, the Malus coronaria, a native Michigan apple tree, learned to fight frost by blooming two or three weeks later than trees that produce apples like Honeycrisp or Red Delicious.
“That doesn’t sound like a lot, but almost always, that’s enough for the flowers to escape the killing spring frost,” said Steve van Nocker, a professor and plant geneticist at Michigan State University.
His goal is to identify the genes that are responsible for delaying Malus coronaria’s blooms and use them to develop more apple varieties resistant to frost. The process will take decades to complete. He is starting by hiking through forests to search for the trees.
Other approaches are being taken to boost the resilience of apples. Growers in Europe and South Korea are currently experimenting with solar panels in orchards and vineyards. The panels protect the apples from sun damage and hail while letting in light and heat.
Recently, researchers at the University of Maryland announced the development of an apple variety that better tolerates heat and a team at Penn State University built a vehicle fitted with a propane-fueled heater that can roll through an orchard, warming up trees as needed.
According to Jared Buono, the director of Cornell University’s Hudson Valley Research Lab, these efforts can help minimize the impact of unusual weather. On May 18, 2023, a frost damaged trees across New York state, reducing apple production by 20 percent.
The unpredictability of climate change makes growers’ jobs even harder. In a recent study from Washington State University, major apple-growing counties in the top three U.S. states for apple production—Washington, Michigan, and New York—are experiencing fewer cold days and more warm fall nights.
The trends in temperature could affect the timing of blooms, bring trees out of dormancy too early, and elevate the risk of sunburn. That’s why it’s so important to study trees like Malus coronaria.

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Malus coronaria is also known as sweet crabapple. The trees used to be so common in Michigan that its blossoms were designated as the state flower in 1897.
However, the species seems to be in decline. Parking lots and shopping centers have taken over the places where the trees once stood. The trees that are left often produce very little fruit. The fruit is also small, green, and bitter.
During their hike, Van Nocker and colleagues cut off small pieces of stems and tested them to ensure that they were Malus coronaria. The cuttings will then be grafted onto an apple rootstock, which will allow them to grow into trees.
The Malus coronaria project can help the researchers create a genetic stock that breeders can use to develop later-blooming commercial apples.
“With climate change, it’s quite possible that apples won’t be able to be produced in Michigan in the future,” said van Nocker. “That’s why cultivar improvement, especially in terms of frost resistance, is so important.”
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