By Scout Nelson
As the meteorological winter concludes, Minnesota's farming community braces for the potential rise in pest populations. The state, known for its cold winters that naturally suppress pest insects, experienced a significantly warmer winter in 2023-24.
This shift has sparked concerns among farmers about the upcoming growing season and the likelihood of facing severe pest-related issues.
January 20th marked the coldest night of the winter, with temperatures dropping to -15 °F in central Minnesota and below -20 °F in the north. These temperatures may not have been sufficient to impact pests significantly.
Insects, being cold-blooded, can survive well below freezing thanks to antifreeze-like compounds in their bodies. The warmth of the soil, barely below freezing even during the coldest periods, offers additional protection to pests like the western corn rootworm, whose eggs overwinter in the soil.
One key pest, the soybean aphid, typically sees population declines at temperatures between -25 and -35 °F. Yet, this winter's mild conditions mean minimal mortality is expected, potentially leading to higher risks for the 2024 crop season.
In contrast, previous years with colder winters, such as the polar vortex in 2019, showed significant decreases in pest populations, including near 90% mortality rates for soybean aphids in northern Minnesota.
Corn rootworms and alfalfa weevils, other critical pests, may also have benefited from the warmer winter. Without the protective snow cover and with soil temperatures remaining around 30 °F, the likelihood of significant mortality among these pests is low. This scenario suggests that farmers will need to be vigilant in scouting and managing pests in the upcoming season.
Migratory pests like the potato leafhopper and others that cannot survive freezing temperatures are unaffected directly by the winter's warmth but may start the season farther north and in larger numbers due to favorable conditions in their overwintering locations.
Interestingly, the emerald ash borer, a non-crop pest, also sees minimal impact from this winter's temperatures, with only slight potential for mortality in the coldest areas of north-central Minnesota.
With the anticipation of an earlier and potentially more intense pest emergence this spring, Minnesota's farmers are advised to prepare through proactive scouting and considering resistant varieties where available.
Photo Credit -istock-fotokostic
Categories: Minnesota, Crops