Factors that elevate storage risk

October 2, 2019 – Issue 27

October 9, 2019 - Issue 28

The big issue this year will be high moisture in harvested seeds, but green seeds and dockage can be factors, too. When the grain going into the bin already has moulds and sprouted seeds, this can escalate the storage risk. Here are the major storage risks, starting with moisture:

Moisture. Moisture creates a more hospitable environment for moulds that trigger heating. Clumping is a sign of mould growth. Storage research found that canola seeds at 25°C and 10.6% moisture clumped together after 11 days and visible mould colonies appeared after 21 days. Note that this research was done in small tubes with uniform conditions. With variable conditions in most bins, clumping may occur more quickly in an on-farm situation. Read more in the Canola Encyclopedia.

Canola storage risk is lower if canola is below 8% moisture and 15°C.

Hot canola. Canola binned hot, even if it has low moisture, low dockage and low green, should still be put on aeration. This will even out the temperature throughout the bin, and help remove some of the moisture from respiring seed. Even at low moisture, air movements within the bin could concentrate this moisture. For safe, long-term storage, canola should be conditioned with aeration to less than 8% moisture and cooled to 15°C or less

Green canola. Green canola seeds can increase the storage risk, even if canola is dry and cool. Monitor closely. Small shriveled canola seed, which often comes with high green seed, can mean smaller air pockets between seeds in the bin. Smaller particles will increase the resistance to air flow. This makes it even more important to leave the fan on as it will need to work longer to cool the entire bulk.

Weed seeds. Weed seeds tend to contain more moisture than canola seeds, especially if they are green or immature. These high-moisture seeds may not be enough to elevate overall grain moisture tests, but if these weed seeds congregate in pockets in the bin they can create localized hot spot for spoilage to begin — especially if that canola is also binned hot. Bits of green weed material in the sample increase the risk.

Chaff. Without a spreader in the bin, chaff tends to concentrate closer to the walls of the bin and fines closer to the centre of the bin. This distribution exaggerates airflow problems because air tends to take the path of least resistance. Concentrated areas of chaff, which could be a start point for spoilage, may be a more serious issue in larger bins.

––Insects that enter the bin in harvested grain. In some years, the canola harvest sample can include a lot of grasshoppers, crickets, cabbage seedpod weevils and even flea beetles. AAFC stored product entomologist Vincent Hervet says no insect species that come from the field would be a problem in canola bins in Canada. However, Hervet says Noel White, his predecessor, looked into the potential for grasshoppers to cause spoilage in cereals. White found that dead grasshoppers could induce discoloring of cereal seeds and be the starting point for mold in bins. Hervet: “If there is a lot of dead insects coming from the field, to prevent the development of mold the seeds should be dried as quickly as possible (if moisture content is high). The study was not done on canola unfortunately, but there is a good chance that there would be a similar issue with canola, especially because canola seeds needs a lower moisture content to preserve well.” To be sure, stored canola should be conditioned which will reduce the likelihood of an issue even further. More on stored grain insects.

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