Cereal leaf beetle (CLB) adults and eggs have been spotted at low levels in some of the YEN cereal sites being monitored this year. Best to scout fields with a known history of CLB activity soon and plan to check all cereal fields a few times over the next few weeks until the head is fully emerged to spot any infestations and injury.
CLB adults are metallic, blue-green in colour, with a reddish-orange head and legs. CLB eggs are yellow and football shaped and are laid flat on the upper leaf surface, close to the midrib. The larvae appear shiny brown to black, like a dirty drop of water on the leaf. The yellowish-beige humpbacked larvae are covered in their own fecal matter to stay moist and protect from predators. A good indication that you have CLB in your field is if you find black streaks across your pant legs after walking through the field.
Both larvae and adults feed on the leaf surface, chewing long scratches that run parallel with the leaf veins. Leaves become skeletonized or window-paned. Heavy infestations cause the field to look silver and similar to frost damage from a distance. Injury to the flag leaf is the most important to avoid.
Examine 20 plants in five locations across the field. It is important to scout various areas of the field, as CLB tends to be unevenly distributed across the field. Record the number of beetles and larvae found per plant. Scout every 5 days, as damage can increase dramatically within days.
If an average of three larvae per tiller are found before boot stage, spray is warranted. One CLB adult or larvae per stem warrants control after boot but prior to heading.
Thankfully, there is an additional product to use if CLB reaches threshold this year. Cereal leaf beetle has been added to the Decis 100EC label (for Eastern Canada only) for use on wheat, barley and oats. Thanks to Bayer for getting this pest approved on the label! This will give growers another tool for cereal leaf beetle control, as we had been limited to only Malathion, which was in short supply in 2024. More information on products for CLB control can be found on the Crop Protection Hub.