By Chris Dervaric, Sylvite
You’ve got your fertilizer down, your preferred population has come up, you’ve managed the weeds and applied the fungicides and insecticides to be faced with the last hurdle of the field season. Frost.
Typically, the risk begins in late September into early October depending on whereabouts you are in the province. Further, the extent of damage is dependent on a few factors such as crop maturity, field topography, temperature reached, and duration of frost temperatures.
Frost can result in yield loss via test weight and silage quality if the frost hits prior to crop maturity.
The Details of Frost
Now, there are two severities of frost: light frost, and a killing frost. Now a light frost is when the temperature reaches 0°C. In corn, this kills the leaves above the cob, turning them light green to grey. But the good news is that because the stalk is generally left alive, cob fill continues through the stalk’s energy reserves.
Similarly, a light frost on soybeans will kill the top leaves, leaving them dehydrated. The top small pods may also be killed. But this still allows for the remaining pods to fill through the energy reserves in the stalk.
Now a killing frost is exactly that, killing the plant at -2°C or lower temperatures. For both corn and soybeans this will kill the stalk, leaves and pods/cobs. Completely stopping grain fill.
Post-frost
You’ve been hit with a frost; what now.
The first thing you should be doing is scouting the morning after the frost. Things you are looking for include:
How far down does the damage extend? The leaves will be grey-green and dehydrated.
For corn: is the crop lodging?
The Takeaway
It’s nice to know what’s happening in your fields and in surrounding areas in season. But realistically, by the time September and October come around, there is not much you can do besides cross your fingers you don’t get a bad frost and know the symptoms of frost damage so that you are not surprised at the elevator. This being said, one option is to monitor the weather and adjust your harvest timing to remove crops before the frost hits. But this may increase your drying costs.
The best thing you can do if you get frost damage is record the date it happened. Further, you can contact one of our Sylvite Agronomists to help keep track of your different frost dates field-by-field, year-after-year. This can help us to recommend soybean and corn varieties that are expected to do better on your soil, with your Crop Heat Units (CHU).
