Despite some brief and isolated cold snaps, the 2019-20 winter shaped up as one of the warmest winters on record. December average temperatures were near record highs for most of Indiana. While a mild winter is pleasant, and is even beneficial for seasonal some crops, like wheat, alfalfa and hay, it can pose a negative for row crop acres in the following growing season.
It’s generally understood that a severe or a mild winter affects insect survival in terms of population size. Research tells us the impact can be dramatic. During a mild winter, approximately 10% of overwintering bugs die, allowing 90% to survive. Conversely, a harsh winter can mean up to 80% die and just 20% survive into spring.1
This means that the 2019-20 Indiana winter is likely to mean increased pressure of key soil-borne pests, along with corn earworm, cold-hardy European corn borer and soybean aphid. Corn earworm had a major impact on our late-planted corn last season and developed high populations farther North than we typically see, which limited thresholds. Corn earworm management is most effective when planting resistant hybrids and alternating planting dates to avoid high densities of the pest. Early planted crops are more likely to escape peak population of egg-laying moths.
Weeds are another potential concern following a mild winter. Prior to planting farmers should expect early emergence plus an increase in weed populations. The earliest weeds to emerge include kochia, lambs quarters and common and giant ragweed. Redroot pigweed and water hemp emerge later, making timing of postemergence herbicides somewhat tricky.
Early emergence weeds can be effectively controlled by using postemergence herbicides after seedlings have emerged. By comparison, later-emerging weed species are best controlled either with a strong preemergence program, a timely postemergence programs, or a combination of the two to aim for extended control. Using a postemergence herbicide is where application timing becomes critical to control both early and later-emerging weed species. Weeds like lambsquarters, pigweed and waterhemp have extended emergence patterns that may require a combination of control strategies.
Finally, excess moisture and intermittent freezing in late fall delayed or prevented some fertilizer applications in many areas of Indiana. This means a wet spring could delay or even overlap with planting when equipment and hours are limited.
To avoid issues related to our mild winter, consider securing your fertilizer needs now, discuss your weed management strategy with your local retailer, and make sure your planting equipment is dialed in and ready to go.
Commercial Agronomist, Indiana
1AGPRO. 2015. Winter weather effects on insect populations.
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