The warm spring days have encouraged plant enthusiasts to venture outdoors and enjoy the bright colors of spring. It can be disappointing to find a favorite plant showing symptoms of distress.
Evergreens that show abnormal browning are especially noticeable in the spring. This injury is given different terms, including winter desiccation, scorch, or winter burn. The damage tends show up as it begins to get warm in the spring. In addition to needle browning, some branches may die.
There are a number of factors that can lead to browning of needles. Dry winds and bright days can cause more moisture to be lost from needles than can be replaced. When the soil is frozen or low in moisture, the roots cannot pick up enough water to meet the demands of the plants. Symptoms are often most severe on the south and southwest sides of evergreens.
In addition to lack of water, many other factors can lead to browning of needles. Rapid fluctuations in temperature, especially in the fall before plants have time to harden off, can injure plant tissues. Salts that are used to treat icy roads can be damaging to evergreens, especially white pines. Rabbits can be problematic, chewing on scattered branches or even the trunk of small plants. Plants that are stressed from poor site conditions or environmental factors are often more susceptible to winter injury than healthy plants.
The severity of winter injury symptoms is typically related to a combination of factors. Identifying the factors that may be contributing to poor plant health will help limit damage from winter stresses in future years.
The best way to prevent winter desiccation injury is to be sure evergreens get enough moisture in the summer and fall when conditions are dry. Mulching trees with an organic mulch, such as wood chips, can also help maintain soil moisture.
Prune dead branches from evergreen trees. If you're not sure if the branch is actually dead, be patient; wait until the buds break. Branches that are still living will eventually show new growth emerging from the buds.
If your evergreen trees have some brown needles instead of healthy foliage, their appearance should improve with time. The brown needles will eventually fall from the trees.
Dead branch tip on bristlecone pine.
Browning of needle tips on a lodgepole pine -- yellow needle color is normal.
This article originally appeared in the 4/13/2005 issue.