Spring Cold Snaps: Effects On Crops

 

Every year is different for crop producers in terms of seasonal weather conditions. Below freezing temperatures recently swept across eastern South Dakota. Crops respond differently to the weather stress depending upon growth stage and habit. In the second half of May, we can expect summer crops such as corn and soybean to be at planting or emergence stage whereas cool season crops like wheat and oat could be further ahead in the developmental stage.

 

 

 

Winter cereal crops such as winter wheat and rye are planted in the fall and acquire early growth before winter weather conditions onsets. Under favorable fall conditions, these plants can grow up to early tillering stage (2-3 tillers). With the arrival of spring weather conditions the subsequent spring winter cereals pick up rapid growth (depending upon varieties) and develop ahead of spring planted cereals.

 

The growing point or crown in annual cereals are located underneath the soil surface and do not emerge above ground until stem elongation or jointing stage. Spring weather in northern regions often fluctuates with occasional nighttime freezing temperatures. This affects winter cereals more than spring cereal crops. Along with winter wheat, rye is gaining interest among growers due to its winter hardiness, good quality forage/cover crops and/or good grain yield. Due to its rapid spring growth, winter rye could be ahead of other small grains at any given time in spring. Small grain crop at or beyond jointing stage could sustain moderate to severe freeze damage if the temperature is below 28° F for two or more hours.

 

If the cold fronts are immediately followed by warmer conditions, fields could be visited for injury assessments a few days after the cooler conditions move out of the system. Plants at the jointing stage will show symptoms such as leaf burning, yellowing, and death of growing points, whereas plants at the boot stage can suffer spike injuries such as floret sterility in addition to those received by plants at the jointing stage.

 

 

Corn plants, like small grains have growing point under the ground until V4 stage (four leaves with identifiable collar). Before this stage cold temperatures can set crop growth back somewhat but they grow back when temperatures warm up.