Cultural Management of Flea Beetles

High populations of flea beetles can completely destroy young stands of Canola. Flea beetles emerge around May 20 in North Dakota. Cool spring weather may delay emergence from overwintering sites such as shelter belts, rock piles and road side ditches. Flea beetles cause more damage in warmer, dryer environments. Management strategies that include these factors will help reduce damage.

Planting in early May will maximize plant size before flea beetle emergence. The larger plants may outgrow flea beetle feeding injury. Planting into stubble may also reduce injury due to the cooler micro environment created by stubble shading of surface soil. Cooler temperatures at the soil surface slows down flea beetle activity, reducing damage. A third management tool to manage flea beetle damage is to use a higher seeding rate. Canola adapts well to various seeding rates without yield loss. However, increasing seeding rate also increases cost and may not be sufficient to prevent stand failures in high population years. Early planting in stubble at a high seeding rate will maximize cultural control of flea beetle. In low to medium population years, this management strategy usually results in adequate stands. Post emergent insecticide treatments may be necessary to insure an adequate stand in some years.