High grain prices, high input costs and better than average yields add up to a lot of risk.
As a result, it’s vital to devise a storage strategy ahead of time to avoid insect and moisture damage.
The place to start is a thoroughly cleaned bin, whether it’s a flat bottomed grain bin on wood, steel, asphalt or concrete or a hopper bottomed unit.
Brent Elliot of the Canadian Grain Commission said it’s tempting to take hopper bottomed bins for granted by not removing all of the grain and sweeping out accumulated dust.
“Insects can survive in even small amounts of cereal grain that is left in a bin,” he said.
“If the bin has a fan and aeration system for drying, that can get grain inside it, in tubes. Insects can be lurking in there.”
Saskatchewan Agriculture entomologist Scott Hartley said producers must avoid creating habitat for insects such as the rusty grain beetle, which is the Prairies’ most common grain pest. In some areas, the foreign grain beetle and red flour beetle can also be problems.
Elliot said producers can use high pressure water or air to ensure their bins are clean, but this method requires caution.
“They also need to be dry, so with water you need to make sure they get a chance to air out if you use water.”
Hartley said producers may use insecticides such as malathion to treat their bins, but this is only allowed for cereals. Other crops, such as canola and flax, absorb the pesticides and will potentially breach internationally acceptable maximum residual limits for trade.
“It can be useful for older bins (for cereal storage), where getting it really, really clean is an issue. Or where you suspect there might be a problem.”
Elliot said grain should be as flat as possible at the top of the bin to avoid uneven moisture concentrations.
“I know that can be a challenge and we don’t advocate climbing into the bin to do it, but where it can be done it can help, especially if you are storing it for a longer time,” he said.
Grain is an excellent insulator and will develop its own air currents that circulate throughout the bin. While this means the air will remove moisture and energy from grain in one area, it will also deposit it in another, creating hot and moist grain pockets.
Hartley said that is an ideal environment for insect development.
“We’ve had great harvest conditions for the most part. Hot days,” he said.
“Grain is dry and you put it away in the bin and two months later you have spoiled grain and bugs.”
This happens because of air movement within the bin. The cooler bin sides cool grain, and the air falls on the outside and rises in the still hot core.
These convection currents help water vapour migrate to the cooler walls and bin roof, where it condenses and eventually meets grain. Heat also encourages fungal growth, provided there is moisture, which creates more insect habitat.
The grain should be aerated or cooled to less than 15 C as soon as possible if the moisture content is less than 14.5 percent. Reducing the temperature to 18 C, provided it is dry, generally renders it safe for storage.
“Bugs don’t do a lot of feeding or growing below 15 degrees,” Hartley said.
“Luckily, winter will come and the grain will get there, provided it hasn’t started to heat.”
Grain monitoring cables can be placed in the bin before loading. These can give readings on temperature conditions within the bin.
The grain’s convection currents will be minimized when the temperature gradient has stabilized within the bin, and the grain will store safely.
The grain commission recommends checking stored grain every few weeks until it can be reasonably assumed that the grain is dry and the temperature stable.
Grain vacuums are effective tools for killing insects at any stage of development. Diatomaceous earth is also effective, especially when added preventively to dry grain as it is placed in storage at harvest.
Malathion is also effective when added to grain as it is transferred. Phosphine, carbon dioxide and a combination of the two can be used to fumigate bins with insect problems.
Chlorpyrophos, diazinon, dichlorvos, dimethoate and other insecticides such as pyretherins are registered for use to prevent insect development when treating corners and hard to clean areas.