Recent Cold Snaps
Every year is different for crop producers in terms of seasonal weather conditions. Recent weather, especially last month or so has been fairly fluctuating. Warmer temperatures, especially in March, have prompted producers for early start on planting spring cereal grains. In South Dakota, winter wheat has come out of dormancy and most producers have already proceeded with spring cereals such as oats and spring wheat. The recent (April 9th 2017) USDA weekly crop progress report shows that 23% spring wheat, 17% oats, and 4% barley have been already been planted in South Dakota.
Even though, some recent days have been fairly warm, some days had below freezing low temperatures. Due to these cooler days some producers have shown concerns about effects of cooler temperatures on small grains, especially winter wheat and some emerged spring wheat and oats.
Impact on annual cereal grain crops.
Different crops respond differently to the cold weather conditions and largely depend on growth stage and habit. Winter cereal crops such as winter wheat and rye are planted in the fall and acquire early growth before arrival of winter weather conditions. Under favorable fall conditions, these plants can grow up to 3-4 tiller stage. In the spring, with the arrival of warmer weather conditions winter cereals pick up rapid growth (depending upon varieties) and develop ahead of spring planted cereals. Cereal crops can show rapid growth even when the growing point or ‘crown’ is still underneath the soil surface. The crown does not emerge above ground until stem elongation or jointing stage. Cold snaps in late spring affects winter cereals more often than spring seeded small grain crop because of the likelihood of emerging crown above the soil surface. 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.