Western Bean Cutworm Update 2015

Author: Jen Bruggeman, Research Assistant, University of Guelph Ridgetown Campus

Western bean cutworm adult in whorl
Western bean cutworm adult in whorl

Western Bean Cutworm traps have been up in Ontario for approximately 5 weeks, with nil to low catches being reported until now.  Just this week we have started to see an increase in moth captures, due to our resident population starting to emerge from the soil and due to the storm fronts bringing our “fly-ins” from the US.

We expect peak flight to happen during the last week of July and into the first week of August, starting in the southwest and moving northeast across the province and into Quebec.

Corn is most attractive to the moths at pre-tassel stage. Though it doesn’t hurt to scout fields near tassel now just to make sure a lot of eggs are being deposited in these fields, the bulk of the fields at risk will be those still in pre-tassel close to peak flight (i.e. last week of July).

Last year we experienced WBC’s geographic range expansion to include some areas that were not traditionally at risk and we are expecting that to continue. When moths arrive/emerge from overwintering here and cannot find pre-tasseled corn to lay their eggs on, they will spread out, looking for suitable fields. This puts the later planted corn that is in pre-tassel stage in late July at risk as well as dry bean fields.

There is also a large amount of variability in growth stages of some fields. When deciding on growth stages it is important to get the best representative growth stage of the whole field. This may take a bit more time but will definitely help later with planning scouting and management strategies.

We will keep you updated as peak flight nears and happens. Please re-visit this blog and our WBC Trap Network website for information regarding WBC moth flights etc.