Insects in stored canola will not feed on sound, healthy seeds. However, moisture-loving fungus feeders such as foreign grain beetles, psocids and mites may be found in canola if it’s in poor condition.
Primary stored product insects such as rusty grain beetle, red flour beetle and saw-toothed grain beetle can occasionally be found in stored canola if cereal grain or weed seeds are mixed in with the canola.
If you find insects in your stored canola, take appropriate measures to control the infestation as soon as possible. The presence of secondary insects, such as fungus feeders, may be an indication that your canola is not being stored properly.
Options for insect control
Heat – Insects exposed to a grain temperature of 50C for about 15 minutes will be killed. If your grain requires drying, this may be an effective option.
Cold – Prolonged exposure to cold temperatures will kill most insects. However, grain bins over six metres (20 feet) in diameter will not cool sufficiently on their own to control some insects. To ensure the entire volume gets sufficient cold exposure, aerate or turn the grain while the outside temperature is low. The time required to kill insects depends on the grain temperature. For example:
A grain temperature of -5C takes about 12 weeks to kill most insects.
A grain temperature of -10C takes about eight weeks to kill most insects.
A grain temperature of -15C takes about four weeks to kill most insects.
A grain temperature of -20C takes about one week to kill most insects.
Impact – The physical impact of travelling through a pneumatic conveyor will control most mites and insects in your canola.
How to prevent insect infestations
Adjust combine settings to harvest sound seed and to minimize chaff and weed seeds in the sample. Before binning newly harvested canola, make sure the bin is free of chaff, seeds and foreign material.
If considering a bin treatment, a registered diatomaceous earth product can be used to treat empty bins but should never be used directly on canola seed as the product will not be effective.