Manitoba
Printer Friendly

Manitoba Agriculture, Food and Rural Initiatives

Manitoba Insect Update

June 22, 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.

To be placed on an e-mail list so that you will be notified immediately when new Manitoba Insect Updates are posted, please contact John Gavloski at the address or numbers listed above.


Summary

Cutworms and flea beetles continue to be the biggest concerns. Sunflower beetles are showing up in high levels in some sunflower fields.

Recent Insect Concerns and Observations

Cutworms: Cutworm feeding continues to be a concern, with canola and sunflowers the crops being most seriously affected. In addition to hotspots of cutworms previously reported, there has also been substantial cutworm damage in the south-central part of the province. Some reseeding of canola, in large part because of cutworm damage, had occurred in canola fields near Mariapolis, Bruxelles, Clearwater and Baldur. Cutworms have also been a concern recently on sunflowers in the Waskada area, where some fields have been sprayed.

Flea beetles on Canola: Flea beetles continue to be a problem in some canola fields. In many fields the plants will soon be reaching a stage where they can compensate for feeding by flea beetles. Generally once canola plants get 3 to 4 true leaves the plants can compensate for the feeding. In addition, populations of flea beetles should naturally start dying soon. The photo below shows 2 of the most common species of flea beetles on canola in Manitoba, the crucifer and striped flea beetles, as well as the pitting they do when they feed.

Flea Beetles on Canola

Sunflower Beetles: Sunflower beetles have now starting moving into sunflower fields. Currently it is the adult beetles, the stage that overwinters, that you will find in the fields. Many fields will have only low numbers, but some higher populations have been noted in the Elm Creek area. The economic threshold for sunflower beetles on sunflower seedlings is one to two beetles per seedling on average, when plants are in the 2 to 6 leaf stage.

 

Surveys and Forecasts

Diamondback Moth Forecasting: Counts of diamondback moth continue to be low. Data and interpretations can be viewed at:https://www.gov.mb.ca/agriculture/crops/insects/db/index.html

Bertha Armyworm Forecasting: If they have not been placed out yet, traps for monitoring adults of bertha armyworm can now be set up. Some data from the traps has been reported; so far counts are very low. Data can be viewed at:
https://www.gov.mb.ca/agriculture/crops/insects/bertha/index.html

Crop Scouting Reminders and Tips

The following figure may be helpful to those assessing flea beetle feeding. As mentioned previously, it can be difficult to accurately assess the % defoliation to plants, and in most cases reasonable estimates are all that can be done and all that is necessary. There is a tendency to overestimate, and visually guides can sometimes be helpful. Thanks to Dr. Julie Soroka with AAFC in Saskatoon for providing the following visual guide to different levels of flea beetle damage to canola.

AAFC Saskatoon Research Centre
Flea beetle cotyledon feeding damage scale