Finding out the type and number of pests in your fields has never been more important.
Agrologists and entomologists emphasize the importance of pest scouting this year because of high commodity prices.
Hector Carcamo of Agriculture Canada said as the price of commodities rise, the value of the damage insects can do to crops increases and that reduces the economic threshold for treatment.
Alberta entomologist Jim Tansey said careful use of a sweep net is critical to ensuring bug counts are accurate.
“Spraying costs money, insect damage costs money. The decision is important, so you need to be accurate in your assessment of pest populations,” he said.
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How to do insect field counts with a sweep net:
Before you start: Contact your local agrologist to determine the appropriate number of sweeps to take and the economic threshold for each insect and crop.
1. To make a sweep: Begin at your side and swing the net 180 degrees through the crop canopy so the top of the net is at crop height. If there isn’t a canopy or the crop is short, sweep close to the ground. Take at least one complete step forward, then sweep again.
2. At the end of the last sweep, raise the net above the crop and quickly swing it back and forth to force the insects to the bottom.
3. Grab and hold the net 15 to 20 centimetres from the bottom to trap the insects.
4. Count the insects you have trapped. The counting system you adopt will depend on how well and quickly you can identify the insects in your net, the number of species present and the total number of specimens.
- If you have only a few insects to count: Hold the net closed, invert it through its rim, then slowly open it. Count the insects as they escape, or empty them into a plastic bag or bottle.
- If you have a large number of insects to count: Empty the contents of the net into a plastic bag, seal and place the bag in the freezer for 30 minutes to slow the insects down.
