By Bryan Jensen
Recently, I’ve been hearing discussions regarding wheat disease management. During your disease scouting efforts some of you may have, or will soon notice some unusual insect feeding on the upper leaf surface. That could be the result of cereal leaf beetle (CLB) larvae, which at best, has been a curiosity and rarely an economic pest in Wisconsin.
Feeding is usually described as slender or elongated feeding scars on the upper leaf surface between major veins. These symptoms are often referred to as “window-paneing”. Early instars are pale yellow and have a brown head. Late instars cover themselves with fecal material and are often confused with slugs. However, CLB larvae will have a well-defined head no antennae and 3 sets of jointed legs.
During the 2015 growing season several crop consultants noticed elevated feeding injury on individual plants. However, field averages were still well below the economic threshold. To give you a perspective on economic thresholds, Penn State suggests 1 larvae/4 tillers, North Dakota State University suggest three larvae/plant and Michigan State suggests 1 larvae/flag leaf.
Again, CLB feeding has been more of a curiosity in Wisconsin.
CLB Larvae
CLB Feeding Scars