Veteran blueberry grower Bob Mattila, who farms between Camas and Battleground, Wash., said a surfactant used with pesticides may cause sunburn when used in unseasonably hot weather.
Mattila said he lost 5 to 10 percent of his crop and wants to warn other farmers.
However, a berry crops extension agent at Oregon State University’s North Willamette Research and Extension Center said it’s too early to know if the damage will affect pollination. Associate Professor Wei Qian Yang said the damage was largely to flower petals. In some cases, only one-third to one-half of the petals were damaged, and flowers might be OK.
Wei said it would be wise to avoid spraying when unusually warm weather is anticipated. He suggested farmers read the surfactant label and look for high temperature warnings. He had not seen the product label in this case and did not know what it says.
Mattila said there is no temperature warning on the surfactant label. A surfactant, mixed with pesticide, helps the pesticide spread and stick to the plant, so it won’t be washed off in rain.
While some flowers had patches of damage, others were “completely wiped out,” he said.
Mattila said he sprayed pesticides April 1 and 2, and the temperature reached 88 degrees on April 7. The National Weather Service in Portland said it was the hottest April 7 or record, with a high of 85 degrees at the Portland International Airport.
Alarmed by burned plants he saw afterward, Mattila said he sought advice from Wei at OSU’s North Willamette station. He said Wei immediately suspected an oil-based surfactant might be responsible because another grower had the same problem. Wei confirmed that account.
Mattila said he also questioned the product distributor and was told the surfactant he used is polymer-based, not oil-based. A company representative was not immediately available to comment.
At any rate, Mattila said he’s trying to figure it out but wants to warn other farmers. He said he’s used the surfactant for years and never had trouble before, but noted that he hasn’t seen 88 degrees in early April before, either.
“I wanted to put the information out there so farmers are aware of this,” he said.