Now that Daylight Savings Time has begun, it's time to start thinking spring. As temperatures begin to gradually climb higher during the next few weeks, blooming flowers, chirping birds and budding trees paint the perfect scene of the season.
But early spring often presents us with drab colors and climates as winter leaves us behind. So, before spring transforms the environment into a palette of bright greens, yellows, pinks and blues, the season's rain showers must wash Old Man Winter's salt-stricken sidewalks and mud-trotted lawns away.
There is no denying I've got spring fever, especially after experiencing sudden warm temperatures during a recent visit to the Midwest. As I soaked in the sunshine, however, expecting to see eager green crocus emerging from the soil along the path, the empty brown cavities I noticed within several nearby evergreen trees dampened my excitement for the season.
Specifically in the Midwest, some conifers are suffering from browning and fading needles, and extended drought might be the culprit. Because conifers transpire all year, they don't experience dormancy during winter, as deciduous trees do. Last summer's lack of rain may have affected the root systems of conifers that now suffer from browning needles - a sign their root systems could not support them through winter. And because trees react differently to several environmental factors, drought may affect some trees sooner than others.
Technical Advisor Rex Bastian says drought symptoms typically appear in Northern white cedar, spruce and pine, but all conifers may suffer from browning or fading needles. "Conifers' needles will begin to turn brown once you add moisture stress in the form of wind desiccation or higher temperatures," he explains. "As moisture stress increases, you'll notice an increase in water loss from the needles versus a decrease in how much water the tree can replace via its root or vascular system."
Summer drought periods will also cause more needles to drop in fall - more than what's typical during a normal fall needle cast season. "The tree will shut down those weak branches for good," Bastian says. "It won't spend time or efforts to supply weak branches with nutrients because needles typically drop from lower branches, which are generally shaded in natural systems anyway; most conifers need full sun to thrive." Conifers will usually allocate resources to the top of tree, where conditions can be better, Bastian adds.
Although drought damage cannot be reversed quickly, you can help renew the appearance of conifer trees that have been slightly to moderately affected. "On conifers, shoots of new growth develop at the tip of each branch, so you may prune or remove the thin or weakened branches near the bottom to improve appearance," Bastian says. "Good shoot growth at the top of the tree indicates good vitality."
With the exception of cytospora canker, a disease that characteristically affects the lower branches of spruce trees, partial browning of needles may not be a sign that the entire tree is at risk. "Conifers' lower or weak branches are often shaded, so they'll lose their needles anyway - this is a normal process," Bastian explains. "You can't control a natural occurrence."
Although drought often causes conifers to brown and suffer from dead or weakened branches, Bastian explains why you can't always blame a lack of rain for the symptoms you see on your trees. "Every year, we expect a certain percentage of stress and varying states of health among all trees," he says. "When you increase the number of environmental stressors, the likelihood you'll see symptoms also increases." For example, Bastian says overwatering causes the same symptoms as extended drought.
Whether drought has affected your conifers, contact your local arborist for a professional consultation of your trees, should you notice any symptoms. The arborist will help you assess the appearance of your trees and make recommendations for proper soil care, mulching and moisture conservation to nurse your trees back to good health.
Looking ahead to the summer months, an arborist may also help determine whether preventive care options exist to protect your trees from further drought damage. "Depending on the situation of your trees, you might be able to take some action to reduce future losses," Bastian says. "Use your arborist's consultation as an opportunity to find the best solution from the available options."