Winter injured conifers
NDSU Extension Agent
By Ashley Stegeman
Dates to Remember
May 31 – Clover Classic Sporting Clays Event, Capital City Shooting Clays in Bismarck.
June 3-6 – North Dakota State FFA Convention at NDSU.
June 3 – 4-H Dairy Judging Contest at NDSU.
June 6 – State 4-H Meat Judging Contest at NDSU.
June 7 – Missouri River 3-D Archery Tournament at Nishu Bowman, Bismarck.
June 7 – Morton County Fair 4-H Clean Up Day in New Salem.
June 9 – Morton County Consumer Choice Contest at Christ the King in Mandan.
The soil temperature at the NDAWN site south of Mandan on May 23.
Bare Soil – 64 degrees F
Under Turf – 49degrees F
Winter injury on conifers
The symptoms of winter injury in spruce trees are often somewhat different. Needles turn different shades of purple, red or brown. Usually, there is no specific pattern to the damage – the discoloration isn’t above the snow pack, or just on one side of the tree. It isn’t necessarily newer needles, or older needles, or needles on the tops of the twigs that are affected. That makes diagnosis a little difficult – environmental problems usually show some type of pattern. Nevertheless, if symptoms like these develop over the course of the winter, after January, then it’s almost certain that the problem can be categorized as winter injury.
While rough winter conditions can kill needles, the buds that contain next year’s growth often survive. Watch out for pests and treat them as needed. Spruce trees that have been damaged by spider mites are more susceptible to winter injury than those that haven’t been attacked. Minimizing drought stress is also important. Make sure the tree has enough water to meet its needs, but don’t over water. In the fall, watering up until the ground freezes will help keep the tree hydrated going into winter. This will help to minimize winter injury, though it won’t completely prevent it. Helping the tree to build new leaf tissue can also support its recovery. Adding a small amount of nitrogen fertilizer in the spring – one to three pounds of nitrogen per 1000 square feet of soil surface – can help the tree to recover.
Winter injury is common and reveals itself as dead needles during the spring. Minimizing stress during the growing season can help trees recover from winter injury, and in some cases, can even lower the probability of winter injury from happening in the first place.