Dave Pike Ph.D.
Although most parts of the U.S. have experienced some brief periods of very cold temps this winter, overall temperatures have been several degrees above normal for this time of year. Short and longer term forecasts suggest that this warming trend may continue, perhaps heralding an early planting season. While it is still too early to say that this trend will hold, there are some generalized concerns that often accompany a warm winter and spring. We list below some events, not as predictions, but as potential occurrences that could follow an early spring and are worth considering as we prepare for the upcoming cropping season.
Early season warming encourages growers to till and plant earlier than normal, and a warm spring will not necessarily reduce the risk of frost damage to the crop. Spring weather is known for its wild fluctuations in temperature, and Alberta Clippers are not necessarily held back because the overall prevailing temperatures to the south have been greater than normal. This is where keeping our eyes on the long term forecasts can help us avoid making replant decisions.
If we do experience an early spring, not all soil and growth conditions are likely to be optimal for the emerging crop. Because days are shorter and the sun is at a lower angle in the early spring, soils tend to warm slower and crop emergence and early growth will be slower than they would be later in the season. Corn plants growing in cold soils can show the purple-stem symptoms of reduced phosphorus uptake and may have a tinge of yellow as nitrogen uptake is also limited. Cool soils can also result in herbicide injury to the crop, or, if herbicides have been applied at marginal rates, they could be leached from the soil or broken down before the slowly developing crop has formed a shading canopy. Some seedling blights and root diseases may also be more evident when the crop emerges slowly.
Another result of a warmer winter is that pests that overwinter are more likely to survive in greater numbers and emerge earlier. Examples of a few such pests in the Midwest include: bean leaf beetles, Japanese beetles, corn rootworms, flea beetles, and nematodes. While some insects, which have multiple generations in one season, will have more time to build to destructive levels, some beneficial insects, those that prey on the destructive ones, may be more prevalent. Similarly, crop diseases may be more prevalent after a warm winter, especially in fields with a high percentage of surface crop residue remaining.
One of the more notable effects of a warm winter is that migratory pests, which do not normally overwinter in areas north of the Gulf states, survive in greater numbers in southern states. The southerly wind and storms will bring these pests much earlier in the season to states in the north. Examples of such pests include, but are not limited to: cutworms, armyworms, common and southern rust in corn, Asian soybean rust, and stripe and stem rust on wheat.
Scouting fields is more important than ever in a season with an early spring. Should warm weather continue to prevail, our slightly foggy crystal ball shows that the pests to be on the lookout for in 2017 will be aphids and rusts in wheat, bean leaf beetle in newly emerged soybeans, and cutworms and armyworms in corn.
To stay on top of developing weather conditions, subscribe to our Weekly Ag Forecasts by Agrible® staff meteorologist, Eric Snodgrass. Eric's videos and commentary are presented with the grower and agronomist in mind. As soils warm and field operations begin, the insights you gain from these videos and the suite of predictive analytics tools in Morning Farm Report® will help you make accurate and timely decisions.