New pests on the way

Tuesday, July 15, 2008

by BETTER FARMING STAFF

For years, the Asiatic Garden Beetle grub was considered to be a pest mostly to flowering plants, and simply a minor one in a “long list,” says Dr. Christian Krupke, an assistant professor specializing in vegetable crops entomology with the University of Guelph’s Ridgetown campus. That changed last year when researchers found the insect in several Indiana cornfields close to the Michigan border feeding on corn roots.
 
The infestations took place early on in the growing season (the insects’ larvae feed on roots from April into early June) on fields with sandy soil. They left behind poor stands and weak plants. Krupke, who had been teaching at nearby Purdue University at the time, says the damage was “economically significant.”

The attack stumped field crop scientists. “We don’t understand why those fields were so devastated and others had none,” he says. Moreover, because it’s a new pest in field crops, there are no control methods in place.

Jocelyn Smith, a research associate in field crop pest management at Ridgetown, says the insect looks like the European Corn Chafer. The difference is a distinctive “pouch” on the beetle’s jaw.

Tracey Baute, the province’s field crop entomologist, predicts the insect won’t pose a problem for Ontario crops in the near future but we “definitely will get it.” In the meantime, she says it’s important to get those involved in crop diagnostics in the habit of searching for the insect’s identifying characteristics.

However, it looks like the Western Bean Cutworm has arrived in Ontario.

Baute says she caught her first WBC moth earlier this month. She caught the insect in Port Lambton using a pheromone trap.

This year the province stepped up its monitoring program for the insect that has caused significant damage in the U.S. Midwest and is moving east. The larvae feed on ears of corn (field, sweet and seed) and on the leaves and bean seed of dry beans (but not soybeans). They may also attack to a lesser degree tomatoes and nightshade. One larva alone can cause a 3.7 bushel-a-year loss in corn.

Smith, who has also been involved in monitoring efforts, predicts the insect could cause a small amount of damage in fields this year, as it did last year in Michigan. But she emphasizes it takes years for the pest to become really established.

It won’t be a huge pest here “anytime soon,” she says. “We are telling everyone about it because we want people to be aware and to look for it.”

The two insects were among the many potential crop problems and treatments highlighted at this year’s Southwest Crop Diagnostic Days held July 9-10 at the Ridgetown campus. The annual event provides training for crop consultants. Attendance was way up, says Baute, this year’s chair for the session. BF