Winter injury

Winter injury is again evident across much of southern Minnesota, more so than occurs in most years. Conifer discoloration, scattered dieback in hardwood branches and late leaf emergence in some hardwood tree species have been observed. Mortality of fall planted and fall transplanted trees was also observed. Events that contribute to loss of moisture in plant material and/ or freezing of plant tissues will result in winter injury. This might occur in times when the weather conditions are mild enough for plants to loose water from leaves without the ability to replace it from the soil.

A visit to the Climatology Working Group home page, Climate Journal,, for a review of weather history will lead you to several conditions that could have contributed to the recent winter injury. Below is a sampling of that content.

  1. An uncommon dry spell occurred from November 2002 through March 2003. This was among the driest five-month periods in Minnesota's climate history!
  2. Warm temperatures on January 7th and 8th. High pressure and an unusual lack of snow cover contributed to a very warm January thaw. The warmest January 7th temperature found in Minnesota was 60 degrees at Fairmont. This 60 degrees is the warmest temperature ever recorded on January 7th in the state and the earliest 60-degree temperature ever recorded in January.
  3. Record warm temperatures occurred on March 15-16. After a prolonged period of cold for the first half of March, the weather warmed up with southerly breezes that rapidly ate away at the snow pack over Minnesota. The mercury cracked 70 in a few places in southern Minnesota. Waseca reached 73 on the 15th and Preston reached 73 on the 16th.
  4. All of the above on top of the deepest frost recorded in a decade.