Aphids eyed in Morrow County; Umatilla Country still up in air
By MATTHEW WEAVER
An Oregon Department of Agriculture pesticide administrator says several causes may be to blame for the yellowing and death of 4,000 acres of wheat in Umatilla County.
The case is still under investigation.
"With this many fields affected, there is the likelihood that there could be multiple causal agents exhibiting some form of symptom or stress onto the plant at the same time," said Dale Mitchell, assistant administrator of the department's pesticides division in Salem.
The size and distribution of the fields make the circumstances unique, Mitchell said.
Besides pesticide, other causes could be a new disease or pest problem or the climatic conditions at the time.
"There could have been just the right conditions for multiple things going on," he said. "It's almost like the perfect storm -- there could have been soil conditions, temperatures and weather patterns pulling down the vigor of the plants."
Meanwhile, in neighboring Morrow County, 30,000 to 40,000 acres of wheat demonstrated yellowing and purple tips. Oregon State University's Morrow County Extension is investigating that problem.
Larry Lutcher, dryland crop production associate professor for the extension, said aphids are the "probable" cause of the damage. He hoped to know more within a week.
The original 17 complaints in Umatilla County in November indicated concerns over applications of weed killer near the winter wheat fields.
The Hermiston, Ore., ODA field investigator collected samples from each field, and the department is analyzing them.
Mitchell said the original concerns were associated with so-called "inversion" conditions. During an inversion, pesticide may be suspended and move laterally onto other areas. Such instances are not usually caused by wind, but by other climatic conditions, he said.
Mitchell said glyphosate, a popular weed killer, does not usually create this degree of symptoms over a large area, even during an inversion.
"I'm not saying it couldn't happen, but I find it odd," he said.
The department requested information from commercial pesticide applicators in the area. The department also asked growers to provide information about pesticide applications, cultural practices, seed varieties and seed treatments.
At the same time, department pathology staff and OSU Extension specialists are looking for other potential causes.
Preliminary information indicates some disease symptoms are present. The funguses rhizoctonia, pythium, fusarium and phytophtora are possible in some samples, Mitchell said.
Any conclusions about possible pesticide involvement or violations is three to four months away, he said, due to the number and complexity of cases.
"It will be quite a while until we start piecing any conclusions together," he said.
Most growers in Umatilla County were replanting their fields.
Dave Paul, regional director for the USDA Risk Management Agency in Spokane, advised growers to contact their crop insurance agents and provide a notice of damage.
The damage occurred before the final planting date of Nov. 30, so producers would be required to replant at their own expense, he said.
For farmers who are insured, planted winter wheat that's damaged to the extent growers would not further care for it must be replanted to maintain insurance, "unless the insurance company agrees that replanting is not practical," Paul said.
If replanting a winter wheat is not practical, spring wheat must be planted, Paul said.