2015 Bertha Armyworm Forecast

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Bertha armyworm (Mamestra configurata) was monitored in 2014 using a network of pheromone-baited traps placed in 311 locations throughout Alberta.

Pheromone traps are used to determine the density and distribution of moths. This network of pheromone traps is organized by AARD and individual traps are managed by a wide range of cooperators. Without dedicated and willing cooperators such a comprehensive monitoring system would not be possible. Our cooperators can submit their trap counts using their smart phones with a web based application.

The Bertha armyworm population in Alberta appears to have shifted west and south in 2014. This is likely due to diseases and parasitism in the previous outbreak areas in east central Alberta. There was much less spraying for Bertha armyworm in Alberta in 2014 than in the previous two years.

Although a number of traps were high in west-central Alberta, very little spraying occurred. There was some need for treatment in Stettler and Leduc counties and also an outbreak centered around Foremost in Southern Alberta.

It is difficult to accurately predict the 2015 Bertha armyworm population based on the 2014 moth catch but the trend appears to be higher populations in west central and southern Alberta. If snow cover persists in those areas it will further encourage successful overwintering. Once again it will be critical to have very good coverage of pheromone traps in 2015 to develop an early warning of potential problems during the growing season.

Bertha armyworm populations are normally kept in check by such factors as weather and natural enemies. Generally parasitism rates of 50 - 60 percent in Bertha larval populations have indicated the end of a local outbreak in the following year. As we saw in 2013 epizootic events (disease outbreaks) can have a major impact on the Bertha armyworm populations. With the amount of disease around it is very possible, especially if weather conditions are favorable, to see complete collapse of the population in central Alberta in 2015. Only by continuing the monitoring program will we be properly prepared each season. In addition maintaining the monitoring even in low flight years allows us to pick up trends and better predict when new major outbreaks are starting.

Potential damage from bertha armyworm may be more or less severe than suggested by the moth count data depending on weather and crop conditions and localized population dynamics. An insecticide application is recommended when the larval numbers meet the economic threshold .

Life cycle information
Diagnostic guide
How to assemble a bertha armyworm trap
Video on how to assemble a bertha armyworm trap

The Alberta Bertha armyworm forecasting program has been done since 1995. Provincial government personnel, industry agronomists, Applied Research Associations, Agricultural Fieldmen and cooperating growers maintain the pheromone trap network. The cumulative moth count maps are maintained by Alberta Agriculture and Rural Development.

During the monitoring season and until January the map is a Google map which means you can move around, zoom in and click on the individual balloons. By clicking on a balloon it will show the organization that looked after that trap, what municipality the trap is in, the weekly count and cumulative count (all counts displayed are the average between the two traps at a site). During the trapping season the information is updated as the entries are made into the data collection website. The resolution is not accurate enough to pinpoint the exact location of individual traps.

The objective of the monitoring is to increase the awareness of canola producers to the damage potential of bertha armyworm. Forecast maps DO NOT replace field scouting. No field should be treated for bertha armyworm control without proper field scouting. Moth catches indicate the potential for damage but the actual populations must be assessed. Experience from 2012 has shown us that adjacent fields or even different parts of the same field can have greatly different bertha armyworm numbers.

For more information on this insect and its management contact the Ag-Info Centre at 310-FARM (3276) or bugs.r.us@gov.ab.ca

Thank you David Giffen, Agriculture and Agri-Food Canada, Saskatoon for building the map.
Thank you to the many cooperators that make this system so successful.


Other Documents in the Series

  2016 Bertha Armyworm Forecast
2015 Bertha Armyworm Forecast - Current Document
2012 Bertha Armyworm Forecast
For more information about the content of this document, contact Scott Meers.
This document is maintained by Shelley Barkley.
This information published to the web on January 20, 2015.