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Ministry of Agriculture, Food and Rural Affairs


An IPM program uses control guidelines or thresholds to indicate when to apply pesticides to prevent economic loss. In other words, some damage to the crop is tolerated as long as this damage does not exceed the cost of the control.

For insect pests, thresholds are usually based on the presence of the pest at certain levels. Thresholds for direct pests, which feed on fruit and have an immediate effect on fruit quality, are generally lower than thresholds for indirect pests that feed on leaves, stems or roots.

For diseases, guidelines may be based on the pest’s damage potential. This is estimated through the use of weather models, crop tolerance, stage of crop development and field observation.

Thresholds have not been developed or validated for all pests in Ontario. Even established thresholds require adjustment for different varieties, markets, and crop vigour.

GBM trap in vineyard Basic threshold monitoring table Weather station Click to enlarge