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Air temperatures in central
Illinois as cold as -10 degrees Fahrenheit on a couple of occasions,
coupled with wind chills as low as -25 degrees Fahrenheit, created
dangerously cold conditions. Cold Weather Advisories were issued for
all of central Illinois on a couple of occasions. Looking at the
Lincoln climatological summary for January from the National Weather
Service in Lincoln, there were 19 days in January that were below
normal, with 12 of those being double digits below normal. Due to
limited snow cover during the Arctic blasts, a frost depth of 10 to
12 inches was able to develop for many locations across central
Illinois. That is around 6 to 8 inches deeper than normal. That
frost depth also lasted for several weeks, helping to have more
impact on pests that typically winter in the surface soils.
Such prolonged extreme cold
conditions can have profound effects on agricultural pests and
pathogens, potentially influencing the upcoming 2025 growing season
in Illinois. While some pests may be adversely affected by the harsh
winter conditions, others may remain resilient, and the overall
impact on pest populations can vary.
Impact on Insect Pests
A deep frost depth in central Illinois during winter can
significantly reduce the population of ground insect pests and
pathogens in the spring by killing off a large portion of their
overwintering stages, especially if there is little snow cover to
insulate the soil, leading to a lower pest pressure when warmer
weather arrives; essentially acting as a natural pest control
mechanism by exposing them to extreme cold temperatures below the
frost line.
Some agricultural insect pests
have developed various strategies to survive harsh winter
conditions, such as entering diapause—a state of suspended
development—or seeking shelter in protected environments. However,
extreme cold can still affect their survival rates. For instance,
pests that are not well-adapted to severe cold may experience higher
mortality rates during harsh winters. Conversely, native pests that
have evolved in colder climates may possess mechanisms to withstand
low temperatures, resulting in minimal impact on their populations.
It's important to note that while extreme cold can reduce the
numbers of certain pests, it may not eliminate them entirely.
Additionally, some pests may have life stages that are less
susceptible to cold temperatures, allowing them to survive and
reproduce once favorable conditions return.
Impact on Plant Pathogens
Nathan Kleczewski, Research Assistant Professor at the Department of
Crop Services, University of Illinois at Urbana Champaign states
that plant pathogens, including fungi and bacteria, can also be
influenced by winter temperatures. Some pathogens may not overwinter
as effectively during extreme cold periods, potentially reducing
their prevalence in the following growing season. For example,
certain fungal pathogens that cause diseases like powdery mildew may
have reduced survival rates after harsh winters.
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However, Nathan indicates that
the relationship between winter temperatures and pathogen survival
is complex. Some pathogens produce resilient spores or structures
that can withstand cold conditions, allowing them to persist despite
severe weather. Moreover, fluctuations in temperature, rather than
sustained cold, can sometimes be more detrimental to pathogens, as
freeze-thaw cycles can disrupt their life cycles.
Considerations for the 2025
Growing Season
While the bitter cold of the 2024-2025 winter may lead to a decrease
in certain pest and pathogen populations, it is not a guaranteed
outcome. Farmers and agricultural professionals in Illinois should
remain vigilant and continue to implement integrated pest management
(IPM) strategies. Regular monitoring of pest and disease levels,
combined with proactive management practices, will be essential to
mitigate potential impacts on crops during the 2025 growing season.
In summary, the severe winter conditions experienced in Illinois
during the 2024-2025 season have the potential to influence pest and
pathogen dynamics. While some reductions in certain populations may
occur, the resilience of many pests and pathogens necessitates
continued vigilance and adaptive management in the agricultural
sector.
Resources:
College of Agricultural, Consumer & Environmental Sciences –
Illinois Extension
Department of Crop Sciences, University of Illinois at
Urbana-Champaign.
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