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Manitoba Agriculture, Food and Rural Initiatives

Manitoba Insect Update

June 1, 2009                   

Compiled by: John Gavloski, Entomologist, Manitoba Agriculture, Food and Rural Initiatives, Crops Knowledge Centre,
Phone: 204-745-5668; Fax: 204-745-5690

To report observations of insect activity or control that may be of interest or importance to others in Manitoba, please send messages to the above contact addresses.

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Summary

Flea beetles have recently become a concern in some canola fields. The insecticide in the seed treatments of canola seeded in early-may may no longer be effective at controlling flea beetles. Some localized high populations of cutworms have also been reported in the central region.

Recent Insect Concerns and Observations

Flea beetles in Canola: Flea beetles are a concern in some canola fields. The insecticide in the seed treatments of canola seeded in early-may may no longer be effective at controlling flea beetles. Until canola gets 3 to 4 true leaves, it is quite susceptible to injury from flea beetles. Susceptible fields should be scouted for flea beetle injury.
It is normal to have some feeding by flea beetles, even in fields where the seed treatment is still functioning adequately. The flea beetles need to ingest the insecticide for it to be effective. As a guideline and nominal threshold, 25% of the cotyledon and leaf material injured is the point where application of an insecticide is recommended. Plants can generally compensate adequately for levels of defoliation less than this.

Samples from last week showed that the crucifer flea beetle is now the dominant species being found in canola fields in eastern and central Manitoba. There are still quite a few striped flea beetles in the population however.

Cutworms: Some high populations of cutworms have been noticed in sunflowers in the MacGregor area. Redbacked cutworms appears to be the dominant species. As crops emerge, check for notching on leaves or clipped plants. If cutworms are responsible for the feeding, you will notice the damage but have to dig around the damaged plants to find the cutworms. Cutworms feed at night and hide in the soil during the day. The cutworms are still small; half an inch or less. So it will be important to watch for cutworm feeding through June.

Redbacked cutworm
Redbacked cutworm

 

Surveys and Forecasts

Wireworm Survey: A wireworm survey is once again being conducted by entomologists at Agriculture and Agri-Food Canada in Agassiz, B.C. One of the goals is to determine the species of wireworms that are present in each region of Canada. This can be important information for farmers and agronomists, because some insecticides perform differently against different species of wireworms. It would be good if we could get as many wireworm samples from Manitoba submitted as possible.
If wireworms are found while scouting, collect one or more and place them in a small container (eg. film roll container or pill bottle) along with some loose soil. Samples can be sent to:

AAFC Agassiz
Attention – Todd Kabaluk
6947 Highway 7
P.O. Box 1000
Agassiz, British Columbia
V0M 1A0

Diamondback Moth Monitoring: Data from some of the diamondback moth traps is starting to be reported. So far numbers are very low; most traps with 0 and only a few with 1 or 2 moths. So there is no indication of any major arrivals of diamondback moth on winds from the south.