pest management Weevil pest persists in blueberry fields
Additional species found; growers given tips on how to spot and deal with them. By Grant Ullyot
eevils and nematodes continue to be a persistent problem for the province’s
At this year’s Horticulture Short Course, Tracy Hueppelsheuser, an entomologist with the B.C .Ministry of Agriculture in Abbotsford, reviewed the progress made in monitoring the effect they are having. She told growers that weevil presence was found in 43 per cent of the fields surveyed. In 2012, some new species were found, bringing to seven the number identified. Of these species, only one is native, the rest are invaders. The native species likely came to North America more than 100 years ago, starting in the east and working their way west. “One of the new species we found in 2012 is a green immigrant leaf weevil,” said Hueppelsheuser. “It is a beautiful weevil, a lovely green color, and there are males and females. They are daytime feeders, so you will find them up in the plant feeding in the canopy, and you will find notching up higher, which is an indication that this weevil is infecting your plants.
“The other is a kind of funny one, a spider weevil. It is a tiny one you might tend to ignore, but it does have a tendency to invade your plants in February or March. And when you think your weevil problem is beginning to disappear, you will find them eating the roots of your plants.” Hueppelsheuser used a series of slides to show growers the different species of weevil they could encounter. “The strawberry weevil is one growers are more likely to see in the spring and fall as well.
“I just want to point out that not all insects are bad. There are some good guys out there, like the Caraba beetle, which looks a lot like a weevil but is bigger. It will feed on soil insects, both their larva and the adults. They run really fast so don’t spray these guys.”
British Columbia Berry Grower • Summer 2015 19 BC MINISTRY OF AGRICULTURE
Damage caused by weevil larvae feeding on blueberry roots.
Hueppelsheuser went on to say there are different ways to monitor plants. Look for notching; look for adult weevils just under the soil surface; or in a poor plant find them eating the roots. Checking the roots is a very good way to determine if you have a problem, she says.
“If you don’t watch the roots you might not see the damage.” One of her main messages about management was that if you find any weevils, get after them. You are not going to get rid of them in one year; it
will require work year after year, continued management and continuous monitoring. One other
suggestion she made is check the edges of your field. Weevil infestations begin there and then move into the main part of your crop. Also check the containers the plants are in as they have been known to carry weevil infections. “The insecticides we have registered right now are targeting adult weevils,”
“So you need to be sure your weevils are actively feeding on the canopies so you can target them.
“The insecticides we have are Exirel, Actara and Malathion, and I guess we could add Admire because it is good at controlling aphids.”
Hueppelsheuser advised her audience if they are having problems, or are uncertain about the use of control agents on pests affecting their crops they should refer to the Berries Production Guide for help.
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