YAKIMA — For the growing and harvesting of cherries, timing is everything — and for the past two seasons, extreme weather has struck at the worst times for Yakima Valley cherry growers.
A record-setting heat wave in late June and early July damaged many cherries before they could be harvested last summer, reducing the crop by roughly 20 percent. And in April, a two-week stretch of below-freezing temperatures hurt the flowers and pollination of Yakima Valley cherry trees, growers and tree fruit experts say.
“For our region, the (two-week cold snap) definitely overlapped with the peak in flowering for cherries,” said Matthew Whiting, Washington State University horticulture professor. “I think the cold weather impact is going to be most severe on our stone fruit, especially cherries.”
Two local cherry orchard owners agreed with Whiting’s grim analysis after April saw an average low temperature of 30.8 degrees in Yakima.
After a warmer-than-normal March, 23 out of 29 days (through April 29) recorded below-normal temperatures, according to the National Weather Service’s Pendleton office. Sixteen of those days had low temperatures below freezing, with record lows of 21 degrees at the Yakima airport on April 15 and 17.
“I’m in a very cold spot, so basically I’ve had 100 percent loss,” said Greg Strutner, owner of Moon Blossom Cherries near Gleed. “The stamens on my blooms are all frozen. There’s lots of pollen, but there will be no fruit.
“The biggest problem is it got cold for so long. Even if you had wind machines, it made no difference,” Strutner added. “I have a full-time job, and just have 3 acres (of cherries), but for those who farm commercially, this is going to be devastating to a lot of people.”
Mark Barrett, owner of Barrett Orchards in northwest Yakima, said the stretch of cold temperatures and occasional snow from April 9 through April 23 were combated with wind machines and sprinklers, which can have a slight heating effect even on the coldest nights.
“It’s a mixed bag,” Barrett said. “We definitely have some freeze damage, but we also have some cherry blocks that were in wind and water protection. We just don’t know if they’ll be pollinated.”
The pollination process is dependent upon several steps happening in the right order, Whiting said. These include having pollen that is alive, compatible and available; having that pollen transferred to receptive stigmatic surfaces of flowers (mostly by bees); and having conditions favorable for pollen germination and growth.
Generally, warm conditions accelerate each step of the pollination process, and the process is slower during cold-weather conditions, Whiting said.
“Our two main areas of concern are issues with fruit set — pollination — and cold temperatures damaging floral tissues in trees,” he said. “What’s unique about this year is there were prolonged periods where the temperatures didn’t rise to the point where bees are active.”
Generally, bees hunker down and do not circulate among flowers if the temperature remains below 55 degrees, he said.
“That’s the point above which the bees are active and get out and forage,” Whiting said. “There’s some hope that the flowers that had opened and avoided major damage will still be viable, and that the bees might still set a crop.”
An alternative to bees is applying pollen via an electrostatic sprayer, a service provided by several commercial companies in the region.
“With this technology, bees do not need to transport or move the pollen,” Whiting said. “So under low bee activity, spraying pollen can be a good solution.”
