2018 Cumulative counts for bertha armyworm pheromone traps

Pheromone trapping for the 2018 growing season is now completed with cumulative counts revealing  moths at five of the six sites AAFC-Beaverlodge monitored (Fig. 1).  The site near Fairview had the highest moth counts but the total number of intercepted moths still sits within the "low risk" category used by Alberta Agriculture and Forestry to help predict bertha armyworm larvae during the early pod stages. 

Figure 1.  Cumulative pheromone trap counts (n=1 trap per site) from commercial fields of canola grown in the Peace River region in 2018.  This preliminary data is not to be copied or reproduced without permission.

Growers are encouraged to use the above information to prioritize their in-field scouting.  The above pheromone traps are not precise predictors but remain valuable to growers because they help identify WHERE the moths were flying and WHICH FIELDS TO CHECK for larvae (Fig. 2).

Figure 2.  Late instar bertha aryworm larvae (photo credit: AAFC-Saskatoon).

When present, bertha armyworm larvae should now be moving upwards on canola plants to feed on the developing pods.  The economic threshold for bertha armyworm applies to the larval stages so use the tables posted here to help guide your in-field pest management. 

Remember two important concepts for insect pest management in your canola fields:

• Low numbers of bertha armyworm can fall within a tolerable level where negligible feeding damage may occur but no economic losses will result!  Scout and use the economic threshold values to avoid economic losses!
• Reserve insecticide use only to manage outbreaking populations of bertha armyworm!  Not spraying actually protects and preserves the many natural enemies already actively working for free in fields!

Learn more about bertha armyworm, @FieldHeroes, natural enemies, and use the canola scouting chart to help your canola produce this year!

Contact Jennifer Otani for more information and thank you to our producer-cooperators!