Effects of an Early Frost

John Van Herk, Product Development and Agronomy Manager, Sevita International

This September as Eastern Canada was hit with an early frost, Sevita growers reached out with questions on what this means for their production and premium. Some of the frost events were mild while others were more severe. Frost events can have an impact on both yield and quality. Of the two, quality can be the more significant factor when talking about food-grade beans.

It is said that soybeans will handle a mild to moderate frost well if the soybean seeds in the pods have separated from the pod wall. This occurs as the maturing pod moves from green to yellow to brown in colour at physiological maturity. Moving back from this stage, frosting of green plants can reduce seed size. In some cases, it can create pod abortion or seed abortion. Frosted green plants can have reduced seed set in the nodes near the top of the plants.

With respect to quality, it is very difficult to predict how much damage a frost event may create. It is safe to say that the earlier frost happens and the more severe it is, the greater the chance to develop green seed in the harvested sample. Severe frost events on green plants can force maturity and create situations where chlorophyll is not cleared from the seed. If this occurs on a large scale within a field, it can result in reduced grading. In some cases, for food grade soybeans, it can cause enough seed damage that the production might not qualify for the premium. Frost events that occur after leaf drop generally cause less to no damage.

Once frost damage has occurred, there are few options to correct the damage. In more mild cases, green seed colour can continue to clear out to some degree during rain events on a standing crop. There can be a limited amount of improvement in some situations during storage. These changes can be difficult to predict.

Fortunately, the frost was fairly mild in many of the production areas for Sevita. We are optimistic that quality and yield have not been drastically affected. Speak to your dealer or RSM if you have concerns.

Some of the frost events were a bit earlier than usual in some regions. Growers should continue to consider earlier food-grade varieties for their production area to manage risk. Growers could also consider fuller-season Sevita GM varieties, where quality standards are not as strict when it comes to frost damage.

Whether you grow food grade or GM, Sevita has high-performing genetics for your farm that can help you maximize your profitability.