YAKIMA COUNTY, Wash. – Yakima County has been listed as the largest apple-producing county in the nation facing big challenges from climate change.
According to a Washington State University (WSU) study, researchers analyzed over 40 years of climate conditions that impact the growth cycle of apple trees from bud break and flowering through fruit development, maturation and color development.
With more than 48,800 acres of apple orchards, Yakima County is the most impacted with harming trends in five of six metrics, said study author and WSU climate Deepti Sing.
“We shouldn’t take the delicious apples we love to consume for granted,” said Singh, “Changing climate conditions over multiple parts of the growth cycle pose potentially compounding threats to the production and quality of apples. Moving forward, it would be helpful to think about adaptations at different stages of apple growth that can minimize overall harmful impacts.”
The study outlined the six metrics which were published in journal Environmental Research Letters from 1979-2022.
Extreme heat days, defined as days with a maximum temperature greater than 34 degrees C (93 F) that can cause sunburn as well as other problems
Warm nights when the minimum temperatures were greater than 15 C (59 F) that can adversely affect coloration.
The number of cold days.
“Chill portions”, or the number of colder hours an apple tree needs to be dormant.
The last day of spring frost.
Growing degree days, meaning the number of days above a certain temperature that are conducive for apples to grow.
The study notes that changes in these metrics can impact apple production, changing the time when apple flowers bloom, increasing the risk of sunburn on apples as well as affecting apple appearance and quality.
“What goes on in different seasons can affect long-term health as well as the performance and productivity of the apple tree during that specific season,” co-author Lee Kalcsits, a WSU tree physiologist who leads programming at the Wenatchee Tree Fruit Research and Extension Center. “So what goes on in the winter affects what happens in the spring, which affects the summer, and it just keeps going around in a cycle.”
Kalcsits added that Washington State producers are employing measures such as a project funded by a $6.75 million grant from the U.S. Department of Agriculture to help mitigate the impact of extreme climate events on apple and pear crops.
For more information on this study, go to WSU news online.
