Grasshoppers Migrating?

2009 – Issue 17

Grasshopper migration into canola fields may increase as pasture growth slows and other host crops (e.g. cereals) are swathed, especially in the drier parts of southwestern Manitoba and southern Saskatchewan. Continue scouting for grasshoppers because, if caught early, perimeter spraying may be all that is needed.  A specific economic threshold for grasshoppers in canola has not been established as it is not a preferred host crop, but it is currently considered to be in the range of 7 to 14 per m2, depending on the crop value and cost for control. More information on grasshoppers is available at the following link:http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex6463

A long, open fall is needed to help crops finish but is also conducive to grasshopper egg laying and development. Female grasshoppers can usually continue to lay eggs until freeze up. If freeze up comes late, then increased grasshopper pressure may result next year, especially where relatively high grasshopper populations exist this fall. After freeze up, grasshopper egg surveys will be conducted by the integrated pest monitoring network (AAFC and provincial entomologists) to help predict the grasshopper risk for next year.

 

Canola Watch