Farmers payed close attention to crop moisture levels during heat wave. (Pat Caldwell/The Enterprise)
ONTARIO – Farmers in the area said that the favorable early growing season has allowed them to stave off losses for most of their crops from recent heat waves.
Stuart Reitz with the Oregon State University Malheur County Extension Service said all crops have a temperature threshold beyond which they shut down normal growing processes.
Temperatures greater than 100 degrees cause corn to stop growing, according to a 2015 study by the National Laboratory for Agriculture and the Environment. Reitz said onions have a much lower threshold of 90 degrees.
“Once they go beyond that threshold, these plants actually need less water because they essentially go to sleep,” Reitz said.
He said it’s crucial for farmers to be paying close attention to their soil moisture, how much evaporation was occurring, and the air temperature because proper watering is often the only line of defense in extreme heat.
“You’re kind of just playing with the cards Mother Nature deals you,” Reitz said.
Paul Skeen, president of the Malheur County Onion Growers Association, said onion growers in the region were lucky to have such a favorable early season.
“The onions have done remarkably well considering the weather we’ve had,” Skeen said.
While he wasn’t worried about his onions and sugar beets, Skeen said it’s a different story for his sweet corn seed.
“Sweet corn seed has been getting hurt,” he said.
That’s because extreme heat is coming during pollination. When temperatures are in the high 90s, pollen dies as it becomes airborne. Like Skeen, Trevor Frahm, co-owner of Frahm Farms in Ontario, said his crops such as onion, winter squash, and radish were far enough along in their growing cycle that the extreme heat shouldn’t have a big impact.
Frahm said that he’s applying a calcium spray that acts like a sunscreen for some of his produce. The spray should reduce that heat on the plants by 10 degrees, according to Frahm.
He said when the crops are healthy, he’s not worried most about heat damage. He’s more concerned with a windstorm at this point in the year.
“A high wind storm could be devastating for us at this point,” Frahm said.
For now, Frahm is staying ahead of watering for the heat and hoping that no late summer storms come through the area.
While the Treasure Valley has been issued several heat advisories in recent summers, this summer’s excessive heat warnings were the worst for the area in the last decade, according to Elizabeth Padian, a National Weather Service meteorologist in Boise.
Padian said that’s because of a recent change in how the service issues hot weather warnings in the Northwest.
Prior to this year, the weather service issued the warnings when temperatures were expected to exceed set temperatures — between 100 and 104 degrees for heat advisories and above 105 degrees for excessive heat warnings.
The change allows meteorologists to account for more than temperature when issuing a hot weather warning.
Meteorologists can now factor in the climate of a specific region, the time of year, and high overnight temperatures.
“It’s more representative of how we deal with and respond to heat,” Padian said.