Grasshopper Forecast

December 2009

Grasshopper populations have increased in most areas of the Province and represent a significant threat to producers for the 2010 growing season as indicated in the annual grasshopper forecast map.

Although cool conditions in the early 2009 growing season slowed grasshopper hatching and development, populations were more noticeable later in July, causing damage to a number of crops.  Canola and lentil pods, as well as flax bolls were chewed, clipped and consumed by grasshoppers and had a direct effect on yield.  Partial feeding on pods can cause premature shattering and provides access for moisture and disease that can reduce grade.  Grasshopper body parts remaining in the harvested crop will also result in excess dockage due to "contaminants" in the grain.    

The forecast map is based on observations of adult grasshopper populations during the 2009 fall survey by Saskatchewan Crop Insurance personnel.  The survey includes nearly 1200 sites and reflects the number of adult grasshoppers capable of reproduction and egg-laying.  This provides an estimate of grasshopper eggs that can survive the winter to hatch the following spring and present a risk to crops.

The actual severity of a grasshopper infestation in 2010 will depend primarily on weather conditions in the spring.  The survey and risk map are intended to provide general information on risk levels.  Actual levels of grasshopper infestations in individual fields may differ from those predicted in the 2010 forecast map.

Producers should monitor for grasshoppers once the spring hatch has begun and crops emerge from the ground.  Certain areas are more prone to grasshopper egg-laying.  Female grasshoppers tend to lay eggs in areas with green growth and a potential food source for the hatchlings that are less mobile and cannot move great distances.  Efficient weed control is important as weedy fields are attractive for egg-laying.  Areas with early green plant growth such as field margins, fence lines, roadsides and crops grown on stubble should be watched closely when hatching begins in the spring.

It is important to note and adhere to the label directions and precautions regarding user safety and application of insecticides. 

Be aware of neighboring fields, and consider how these might be affected by the insecticide being applied.  Take special care when using insecticides to control grasshoppers in close proximity to wildlife and near environmentally sensitive areas like ponds, sloughs and shelterbelts.

Most insecticides have broad spectrum activity and can be fatal to beneficial insects such as honey bees, other pollinators and parasitic insects capable of natural biological control, as well as pest species.  Some strategies to avoid a negative impact on bees are:

• Avoid spraying or allowing spray to drift onto flowering crops or weeds where honey bees are foraging.
• Spray in the late evening or early morning when the bees are not flying.
• Contact local beekeepers to provide a few days warning of spraying intentions. 

Keep in mind that the objective is to sensibly control grasshopper populations to protect the crop.  One hundred per cent elimination of the insect is not a realistic goal.

For further information, contact:
Agriculture Knowledge Centre
Toll Free: 1-866-457-2377
E-mail: aginfo@gov.sk.ca