The Washington State Department of Agriculture is encouraging homeowners to think about bees before applying pesticides to flowering plants.
It's part of an effort to reduce the risk to pollinators vital to garden health and the local and state economy because bees pollinate 10 of Washington's top 40 crops.
Pesticides are among the potential causes of the perplexing decline in bee population nationwide. A U.S. Department of Agriculture and Environmental Protection Agency report issued in May suggested parasites and disease, genetics and poor nutrition also were potential factors in what has commonly been called colony collapse.
Washington has not had any severe bee poisoning cases since 2002, when bee deaths were tied to pesticides known as neonicotinoids used on pears, said Erik Johansen, a state Department of Agriculture pesticide registration specialist.
But each year, Washington tends to see two or three incidents resulting in dead bees, he said.
"There has been a growing concern about the health of bees and other pollinators in Washington and across the country," said Bud Hover, the Department of Agriculture's director, in a statement. "Our agriculture community and our environment need these pollinators."
Crops pollinated by bees were worth more than $2.75 billion to the state's economy in 2011, according to the department. Mid-Columbia crops that depend on bees for pollination include apples, cherries and blueberries.
The Department of Agriculture recently decided against creating rules that would limit homeowner use of neonicotinoid insecticides on ornamental plants. It was something Thurston County commissioners requested based on a belief that the insecticides were harmful to the local bee population.
While the department decided there wasn't enough data to limit the used of those insecticides to those with licenses at this point, Johansen said Hover did decide to reach out to homeowners to educate them on use.
Agricultural and commercial applicators tend to have training and licenses, officials have said. The directions on pesticides they use also tend to be more explicit than those that a homeowner may buy at a store like Home Depot or Lowe's.
Essentially, Johansen said they are encouraging homeowners to avoid applying pesticides to blooming plants. Instead, homeowners should apply pesticides before or after bloom, when it is less likely bees will be directly exposed to the pesticides.
"If you can avoid applying when the plant is blooming, that is a huge deal," he said.
While there have been several incidents involving linden trees in Oregon and other states, Johansen said the concern is with any blooming plants.
With pesticides that are applied using soil drench, it's best to wait until after bloom, Johansen said. In that case, the pesticide applied near the roots is taken up into the plant. If it enters pollen or nectar, it could be problematic for any bees pollinating the plant.
In addition, homeowners should apply the lowest rate consistent with controlling the pest and choose a product with the shortest residual to avoid contaminating next season's bees, he said.
Homeowners should also check the labels for any warnings about risks to pollinators such as bees before applying any pesticides, Johansen said.
A pamphlet the department has posted on its website and is distributing also encourages homeowners to wait until after all petals have fallen before using neonicotinoid insecticides that have clothianidin, dinotefuran, imidacloprid and thiamethoxam as ingredients. Those may be highly toxic to bees for several days after they are applied, according to officials.
-- For more information, go to http://agr.wa.gov.
-- Kristi Pihl: 582-1512; firstname.lastname@example.org