Emerging pests in forage corn and grass in British Columbia: Learning to deal with true armyworm (Mythimna unipuncta) and western corn rootworm (Diabrotica virgifera)

Two forage pests, Western Corn Rootworm and True Armyworm, have caused significant levels of damage to forage crops (corn and grass) in the Fraser Valley and on Vancouver Island.

Western Corn Rootworm was detected in 2016 in Fraser Valley for the first time in BC. Rootworm is native to the Americas and has been a significant pest for many years in major corn growing regions of the USA and eastern Canada. In BC, this pest appears limited to the Fraser Valley. Through surveys with traps and visual searches in fields and communication with the agricultural industry and researchers in BC and eastern North America, we have been able to learn about the biology of this new pest in BC and enable growers to implement prevention and control tools to minimize damage to both forage and sweet corn.

The first known outbreak of True Armyworm in BC occurred in 2017, when Vancouver Island and Fraser Valley forage producers of grass, cereals, and corn experienced unprecedented losses. This is a North American insect that is introduced annually in spring to southern Canada on wind currents. Introduction of enough moths to cause an outbreak seems rare in BC. Through surveys (pheromone traps, field scouting) and communication tools (pest notices, presentations) our goal was to enable growers to manage these pests as needed. What we have learned since 2017 has contributed to the understanding of True Armyworm biology and its impacts in British Columbia and other regions of western North America.