Protecting Poplars

Hybrid poplars are among the fastest-growing trees in North America and are well suited for the production of bioenergy (e.g., heat, power, transportation fuels), fiber (e.g., paper, pulp, particle board, etc.) and other bio-based products (e.g., organic chemicals, adhesives). Because poplar trees have so many economic, environmental and agricultural advantages, it is important they are protected.

Hybrid poplars are among the fastest-growing trees in North America.

John Brown, WSU professor, scientist and extension specialist, is leading an award-winning team that is completely revamping the pattern of insecticides used to protect poplar trees. A driving force for this effort is to have the lumber sold under a Forest Stewardship Council certification program.

“When we started our Integrated Pest Management program, poplar growers were relying on broad spectrum insecticides,” Brown explained. “Now they use sex pheromones, insect growth regulators, and systemic nicotine mimics which are delivered through a drip line.” These methods are more environmentally friendly and won’t hamper biological control.

The research team started with a basic laboratory discovery of the pheromone for the Western Poplar Clearwing Moth and developed an EPA-registered insecticide in just four years that disrupts the mating process. The pheromone is aerially sprayed in microcapsules over the poplar trees each month from April to September so that the male moths cannot find the females.

Brown says that his team also is developing a modified Attract-and-Kill strategy where the males of a specific insect species are lured to a synthetic pheromone. When the male insect approaches the pheromone source, it comes into contact with a killing agent.

Insect growth regulators are another method used to protect poplars. “We use insect growth regulators that prevent insect larvae from successfully molting but are not toxic to adult insects, so beneficial insects such as parasites and predators are not harmed,” Brown explained.

Currently, the team is experimenting with tree injection technology to introduce insecticides directly into individual trees. This method is labor intensive but could provide multiple year protection to the trees.

Brown’s research team received both regional and national IPM Team Awards for their Poplar Protection Program in 2006.