Two-year study will target the pest in organic potatoes
By CAROL RYAN DUMAS
Research just funded by USDA's National Institute of Food and Agriculture is aimed at improving integrated pest management in organic potatoes.
The University of Idaho Extension Service will target the Colorado potato beetle in trials to begin at the Kimberley Research and Extension Center in 2011.
The two-year study will compare beetle preference, plant resistance, beetle populations, defoliation and yields in open plots using at least 10 commercial varieties, said Erik Wenninger, UI assistant entomology professor and extension entomologist.
The research could benefit growers by identifying varieties that are more tolerant of beetles.
Previous research at the Kimberly center showed beetles seemed to prefer some varieties over others.
"It could be a preference issue or the tolerance of certain varieties to beetle feeding," he said.
The nearly $109,000 USDA grant will help investigators explore the issue in more detail, including how much odor, color and taste influence beetle attraction.
Resistance to the beetle is an ancestral trait that might have been lost in some varieties, Wenninger said. Natural resistance could be more manifested in some varieties.
"We'll try to get at that question," he said. "We'll look at defoliation rates and population of beetles."
In more tolerant plants, adult beetles might produce fewer eggs because they're not feeding as much and not as healthy.
"Growers could use more tolerant varieties. If they want to grow others, they should be prepared and consider it in their management plans," Wenninger said.
Also, identifying varieties that attract beetles would give growers an option to use those varieties in trap cropping around their preferred varieties, he said.
The researchers will also look into resistance to conventional and organic insecticides.
Conventional growers have a lot more tools available when it comes to insecticides, he said. Organic growers have fewer, more costly options.
The research could help reduce insecticide use, mitigate insecticide-resistance development and reduce input costs.
The main experiment is the side-by-side comparison of varieties in the open plots, but a smaller study comparing plants covered with mesh cages will also take place.
The plants will be artificially infested and caged to prevent further colonization of beetles.
But the study could also show that even in a caged environment, some varieties have better resistance than others.
Along with the agronomic research, the study will provide data for economic analysis of potential returns and risks of organic production in the region and for developing enterprise budgets.
An outreach plan to share the information with growers will be coordinated through the extension system, Idaho Potato Commission and Northwest Coalition for Alternatives to Pesticides.