Bean leaf beetle numbers modest - so far

Sunday, June 8, 2008

by GEOFF DALE

“Some fields are reporting a bit of activity but with the spring delayed it’s difficult to say whether it will be worse than or as bad as previous years,” says provincial field entomologist Tracey Baute.

Mild winters in the past few years have allowed the brightly coloured beetle to flourish and progress further north, she says.

“We’ve had some reports from Iowa down in the States that, based on their modeling, this year may not be as bad as 2007,” she adds. “They’re saying the winter there was much harsher and may have taken care of the insect.

“But it’s still a problem here and producers have to keep a careful eye on seedlings and when the pods are forming.”

In the past the insect was mostly confined to the southwest sector including Huron, Perth, Middlesex and even some parts of Elgin and Oxford Counties but they have been showing up recently in Bruce and Simcoe Counties.

Ontario Soybean Growers research Crosby Devitt agrees mild winters are the chief culprits for the insect proliferation, noting the 2007 season began early so damage to seedlings were recorded in May.

“We haven’t done much formal tracking before but this year, in cooperation with OMAFRA, we started a project that will monitor 35 sites weekly across the province,” he explains.

As for the economic impact the beetle has on the provincial soybean industry, no real dollar figure has been set. However, Devitt stresses the impact on producers’ pocket books can come from: overall yield reduction; pierced pods affecting the seed quality; and cost of preventative measures like insecticides.

Essex County grower Leo Guilbeault, also chair of the growers’ board, says it’ll be into summer before producers can determine the beetle’s impact on the 2008 yield.

“Weather and the area are always the two major factors,” he added. “Two years ago it was severe right from the spring through to the end of the season. But last year it was more isolated and in Essex, there were fewer outbreaks.

“Now there are lots of beans emerging but not a lot of beetles. We’ll wait and see if that pattern continues.” BF