Spring 2022 has brought numerous questions and concerns about conifers, especially for those planted last and the year before. What is going on? The good news is that it is not a disease or insect problem, and no treatments of trees are needed. We are also hopeful that many trees will recover, but read on for what you can do to help your trees.
Why are conifers struggling?
There is no single answer to what is occurring. Like many tree problems, there are several stress factors that are probably at play. The first stress was last year's drought, which was especially harmful to newly planted conifers trying to establish. New trees need to be watered until the soil freezes in the fall, often for several years. The larger the tree at planting, the longer it will need to be watered (3-4 years) because it takes time for the root system to recover and support the aboveground portions of the tree. A second related factor leading to the brown needles is winter desiccation. Winter desiccation is thought to be caused by a combination of extreme temperature fluctuations, strong winds, and sunlight leading to brown needles. Symptom expression is most pronounced on the sides of the plant exposed to sunlight or wind during the winter months.
Is there anything to do right now for my newly planted conifer?
Yes, there is! The next few weeks will be key to trees recovering. We still believe many trees may put on new growth and should do so in the next few weeks as forecasts show warming temperatures. As this new growth occurs, it will be important to check soil moisture and provide water if it is dry. The high temperatures forecasted can quickly lead to water stress. Also, note that conifers do not keep their needles forever, so even complete loss of overwintering needles does not mean the tree is dead. If your tree puts out new growth in the next few weeks, it is a good sign that it can fully recover.
What about my older trees?
Older conifers have also suffered from winter desiccation, but not as much as newly planted trees. They, too, should put out new growth in the next few weeks and start appearing much healthier. Well-established trees should not need supplemental water as they have large root systems that can support aboveground growth.
What can I do this summer?
Any conifers planted in the past 2-3 years or this upcoming growing season will need to be watered, especially if we enter drought conditions again. Despite recent rainfalls, portions of Iowa are still abnormally dry or in drought conditions. Watering should continue until the soil freezes.
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