Is it too Late to Spray Flea Beetles in Canola?

Figure 1. Crucifer flea beetles causing defoliation.

 

Flea beetles have been showing up in many different crops this year. One of the crops that is often affected by flea beetle feeding is canola. There are three species of flea beetles that commonly infest canola and feed on the leaves. They are the crucifer flea beetle, hop flea beetle, and striped flea beetle. The main concern with flea beetle feeding occurs early in the season when vegetation can be rapidly removed by these pests (Figure 1). However, late season feeding can also be a problem.

 

The first thing to keep in mind when scouting fields for flea beetles is that their populations tend to be much higher near field edges. For this reason, the entire field should be scouted to determine how far the infestation goes. Weather conditions can influence flea beetle infestations and their populations tend to be more uniformly distributed during hot, calm days. If the populations are limited to the field edges, a perimeter insecticide application can effectively reduce the populations.

 

For later season flea beetle populations, pod feeding can result in decreased yields and increased number of green seeds. If canola is beyond the 5.2 growth stage (when seeds in lower pods have turned translucent to green) yields will probably not be affected by flea beetle feeding.

 

If late season management is necessary, foliar insecticides will provide the best reduction in flea beetle populations. Table 1 has a list of insecticides that can be used for flea beetle management in canola.