For the most part bertha armyworm populations remain in the low end of their cycle. Only three locations in 2010 exceeded the limit that defines Low Risk: two sites in Two Hills county and one in Provost county. Of these three locations one site exceeded the High Risk threshold. None of these locations resulted in canola crop loss or the need for control operations. These elevated moth catches may be an early warning for higher populations in 2011. Cumulative moth counts in traps during June and July of 2011 will give us a much better evaluation of the population and therefore the risk in August.
|Bertha armyworm (Mamestra configurata) was monitored in 2010 using a network of 125 pheromone-baited traps placed throughout Alberta. Pheromone traps are used to determine the density and distribution of moths. This network of pheromone traps is organized by AARD but individual traps are managed by a wide range of cooperators. Without dedicated and willing cooperators such a comprehensive monitoring system would not be impossible. |
Bertha armyorm 2011 Survey Results will be coming in mid June. Check back then.
For 2010 results follow this link to the Agriculture Canada tri-provincial forecast maps. Please go to the drop-down menu to locate the bertha armyworm map.
Click here to view the 2011 insect forecast video presentation.
Bertha armyworm populations are normally kept in check by such factors as weather and natural enemies. Generally parasitism rates of 50 - 60% in bertha larval populations have indicated the end of a local outbreak. Cumulative moth counts in traps during June and July of 2010 help determine the level of risk for August. The results from 2009 suggest that bertha armyworm is a low part of the cycle.
Life cycle information
How to assemble a bertha armyworm trap
Video on how to assemble a bertha armyworm trap
The bertha armyworm forecasting program for Alberta has been conducted 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.
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.
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 .
The objective of the monitoring is to heighten 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.
Economic thresholds for bertha armyworm
|Cumulative moth catch ||Risk Level||Interpretation|
|0 to 300||Low||Infestations are unlikely to be widespread, but fields should be inspected for signs of insects or damage.|
|300 to 900||Uncertain||Infestations may not be widespread, but fields that were particularly attractive to egg-laying females could be infested. Check your fields.|
|900 to 1200||Moderate||Infestations likely, canola fields should be sampled regularly for larvae and for evidence of damage.|
|1200+||High ||Infestations very likely, canola fields should be sampled frequently for larvae and for evidence of damage.|