Moisture is the Enemy: Preventing Mold and Decay in Grain Storage

The most common problems related to grain storage are caused by moisture and temperature. Moisture levels greater than 15% can lead to spoiled grain, silo blockages, and occupational hazards. High moisture also leads to mold growth, which can compound these storage problems.

Proper silo maintenance is vital to protect grain from being ruined by mold infestations.

There are two classifications of mold that silo owners must address. The first is referred to as field fungi. The second is called storage fungi. Field fungi infect the crop before it is stored in the silo. Storage fungi develop once the grain has been placed in the silo or bin.

Silo owners may not have control over what happens to the grain during harvest and preparation, but they do have control of their silo maintenance. Interior silo temperatures should be kept below 50 degrees and moisture levels below 15% for the best chance to avoid mold.

Common Indications of Mold

Discoloration: Some mold can be identified using the naked eye. The most common type of grain mold is called “Blue-eye” mold, which features blue-green spores. Blue-eye mold is problematic because it can grow at lower moisture contents and may stay in the grain even after it’s been cooled.

Blockages: Silo blockages are often caused by moisture accumulation. Caking can be a telltale sign of moisture and mold. Silo blockages should be removed regardless of the cause, but it’s important to inspect for mold during the cleaning process.

Laboratory Tests: Many molds are microscopic and can be identified only with specialized tools. Silo owners who are concerned about hidden mold can send a sample to a regional grain inspection laboratory (Midwest Labs).

Consequences of mold in grain storage

Financial Loss: Stored grain that has been contaminated by mold is of little or no value for food production. When grain reaches a certain level of mold particles per million (the threshold can vary by elevator), it will be rejected by most buyers or incur financial penalties. 

Mold-infested grain that has been rejected for human or animal consumption may be marketable as an ethanol or fertilizer base.

Health: Mold presents many threats to human health. Allergic reactions are the most common response to mold. Breathing problems, rashes, and sinus issues can all be caused by mold. However, some molds carry poisonous properties that can cause life-threatening complications. These poisonous molds can be found in cereals; oilseeds, such as soybean, peanut, sunflower, and cotton seeds; spices; and tree nuts. Since many of these foods are stored in silos, mold inspections are a must.

Mold Prevention Techniques

Harvest Correctly

Grain must be dried and cooled at harvest. Grain left exposed to the elements has a much higher chance of contracting mold. An early harvest can lead to higher grain drying costs.

Maintain Your Cooling System

A malfunctioning cooling system can leave your grain vulnerable to mold. This is especially important in years with warm fall seasons. Grain should be stored below 50 degrees. By mid-November, temperatures should be cooled to the 40s and then to the low 30s by New Years.

Silo professionals recommend looking for steam rising during the cooling process. Steam indicates moisture being released and warrants checking for the presence of mold. Moldy grain may also emit bad odors during the cooling process. A foul smell should prompt a more detailed mold investigation.

Check Your Grain Regularly

Preventative mold checks will save money, time and effort in the long term. Don’t wait until mold signs become unavoidable. Check grain quality every two to three weeks during winter. In the summer, grain should be checked even more frequently because of higher temperatures and humidity levels.

Sell Low-quality Grain Early

Grain can still be sold with low levels of mold. Almost all batches have some nominal trace of fungus. Silo owners who notice mold growing can try to get it to market quickly. Letting mold grow out of hand can limit selling options and reduce market price. High-quality grain should be saved for later in the season.

Regular cleaning

Mole•Master recommends regular silo cleaning to maintain the quality of your grain and help prevent mold from hiding in older, caked material. Moldy grain that stays in storage year after year has the potential to infect all future crops.

Mole•Master offers turnkey silo cleaning services for all types of grain facilities. We also manufacture silo cleaning equipment for rental or purchase that your maintenance department can use for your preventative maintenance plan.

If you have questions about how to combat grain mold in your silo, contact Mole•Master today. We will connect you to one of our cleaning professionals who can get your silo into top performance.

Contact Mole∙Master™ at 740.374.6726.