Dreary spring slows Oregon farmers, crops, insects
Low temperatures have slowed the growth of Oregon’s crops this spring, at least compared to recent years, while high moisture levels have impeded the state’s farmers.
Crop development in the Willamette Valley, for example, is roughly a month behind 2016 and 2015, according to “degree day” data compiled by Oregon State University.
Degree days represent the accumulated average daily temperatures above a certain threshold — 41 degrees Fahrenheit for many crops — necessary for plant growth.
However, crop development in 2017 is actually close to the usual average. The previous two springs were simply much warmer than typical, according to OSU.
“Even though it’s been quite cool compared to the last couple years, we’re still around the 30-year normal,” said Len Coop, associate director of OSU’s Integrated Plant Protection Center.
Meanwhile, precipitation across Oregon has been 20-47 percent above average during the current water year, which began last autumn, according to USDA’s Natural Resources Conservation Service.
Saturated soils have prevented farmers from applying fertilizers and pesticides or planting vegetables and other annual crops, experts say.
“You’ve got this complication of all the work backing up,” said Tom Peerbolt, a berry crop consultant and founder of Peerbolt Crop Management.
Soggy ground and strong winds knocked over a large oak tree at a ranch near Elkton, Ore., killing two cows owned by Ed Cooley.
Cooley said he realized something had gone wrong when his electric fence failed, which led him to the fallen tree and five cows trapped beneath.
While two were crushed to death, Cooley managed to rescue the other three by removing limbs with a chain saw.
“The cows were pretty calm about it,” he said.
Plentiful rainfall tends to encourage fungal diseases like scab in apples, but low temperatures suppress the emergence of pests, such as the spotted wing drosophila and brown marmorated stink bug, said Coop.
The spotted wing drosophila needs a higher temperature threshold — 50 degrees Fahrenheit — to develop than many crops, so right now, the insect’s populations are lagging plant growth, he said.
The pest would still be at a disadvantage if the weather quickly shifts to being hot and dry, but mild temperatures would allow it to thrive, Coop said.
“They could catch up later on,” he said.
Rainy weather during blueberry bloom reduces bee activity, which could hurt pollination, though the problem is still speculative at this point, said Peerbolt.
Dampness is also conducive to mummy berry, a fungal disease, which is tough to combat with fungicides when windows of appropriate spraying weather are scarce, he said.
“It increases the risks of fungal disease pressure down the road,” Peerbolt said.
The pace of field work is sluggish this spring for growers of sweet peas, which could delay planting of other crops, such as corn and green beans, said Dan Fitzner, scheduling manager for the NORPAC food processing cooperative.
If NORPAC’s processing volume is dominated by sweet peas, that prevents the company from switching to those other crops, he said. Effectively, that means planting of other crops must be delayed or acreage of sweet peas must be decreased.
“It could be a problem if it keeps up like this,” he said.
Some Oregon crops can benefit from the dreary spring.
Perennial ryegrass, a major seed crop in the Willamette Valley, generally performs better in cooler, wetter weather, said Tom Chastain, an OSU seed crop physiology professor.
Rust disease tends to be more problematic on perennial ryegrass and tall fescue — another common grass seed crop — during warmer and drier springs, since the reproductive cycle of the fungus is sped up, Chastain said.
However, annual ryegrass, which is generally planted in poorly drained soils, won’t be helped by the generous rainfall, he said.
The cool spring is a delayed effect of the La Nina climate pattern, which is associated with low Pacific Ocean temperatures, said Coop.
“Every time a La Nina comes around, this is what we expect,” he said.
According to long-term forecasts, though, temperatures are expected to become higher than average later in spring, Coop said.
“The normal seasonal pattern should kick in pretty soon,” he said.