Note that this is not a forecast. It is a summary of the situation in Alberta in 2020.

Methodology

The bertha armyworm (Mamestra configurata) monitoring program has been conducted in Alberta since 1995. A group of keen and dedicated cooperators made up of provincial government personnel, industry agronomists, applied research associations, agricultural fieldmen and cooperating growers maintain the pheromone trap network. Agriculture and Forestry organizes the network of pheromone traps and maintains the map and the web-based application. The Prairie Pest Monitoring Network provides the traps and lures.

In 2020, a network 350 sites of pheromone-baited traps monitored for bertha armyworm across Alberta. These traps help to determine the density and distribution of moths. Moth counts from the traps are submitted using a web-based application that can be accessed using a smart phone.

Without dedicated and willing cooperators, such a comprehensive monitoring system would not be possible. Thank you to everyone who has participated in the pheromone trapping for bertha armyworm.

Survey findings

Bertha Armyworm map (PDF, 5.0 MB)

In, 2020, The bertha armyworm population increased in many locations in Alberta. Trap catches indicated a population on the increase in central Alberta and as far south as at the MD of Willow Creek.

While it is difficult to accurately predict the 2021 bertha armyworm populations based on the 2020 moth catch, it appears the outbreak in the Peace is declining while in central and southern Alberta a population increase is entirely possible.

The pheromone trap system will be important to capture the problem areas that will likely occur in 2021.

It will be critical to have very good coverage of pheromone traps in 2021 to develop an early warning of potential problems during the coming season. This trend, however, indicates that a bertha armyworm outbreak is possible or even likely in Southern and Peace regions of Alberta.

Normally, weather and natural enemies keep bertha armyworm populations in check Parasitism rates of 50 to 60% in bertha larval populations have indicated the end of a local outbreak in the following year. In addition, as we saw in 2013, disease outbreaks can have a major impact on the bertha armyworm populations. Snow cover encourages successful overwintering, in contrast low snow cover with cold temperatures reduces winter survival. Monitoring, even in low flight years, allows us to pick up trends and better predict when bertha armyworm populations start to build-up and lead into new outbreaks.

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.

During the monitoring season, the reported trap counts are displayed on a Google map. The map allows the viewer to zoom in and click on the individual balloons. Clicking on a balloon will display the organization responsible for the trap location, municipality where the trap is located, and both the weekly and cumulative counts. All counts displayed are the average of the two traps at the site. (All counts displayed are the average between the two traps at a site). During the trapping period, the information is updated as the entries are made into the data collection website. The resolution is not so fine as to pinpoint the exact location of individual trap locations.

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 without proper field scouting. Moth catches indicate the potential for damage but the actual populations must be assessed. Experience from previous outbreaks has shown us that adjacent fields or even different parts of the same field can have greatly different bertha armyworm numbers. Producers growing peas and faba bean also need to pay close attention to the bertha monitoring system as bertha armyworm has been known to feed on both those crops.

Acknowledgements

Thank you to Janet Lepp for entering cooperator information into the reporting system for 2020. Your contribution is so appreciated.

Thank you David Giffen, Agriculture and Agri-Food Canada, for translating the trap data into this map.

Historical population maps

2019 Survey Map (PDF, 2.0 MB)

2018 Survey Map (JPG, 1.2 MB)

2017 Survey Map (JPG, 1.0 MB)

2016 Survey Map (JPG, 381 KB)

2015 Survey Map (JPG, 381 KB)

2014 Survey Map (PDF, 2.9 MB)

2013 Survey Map (PDF, 723 KB)

2012 Survey Map (PDF, 568 KB)

2011 Survey Map (PDF, 434 KB)

2009 Survey Map (JPG, 62 KB)

Resources

Bertha Armyworm – Overview

Bertha Armyworm fact sheet

How to assemble a bertha armyworm trap