Extension Educator, Horticulture
What's wrong with my pine tree? A common question posed to me at my office, over the phone, in emails, at the grocery store, at the gas station, and even in the waiting room at the doctor's office. My first question is always, "Do you know what kind of pine it is?" This may seem of minor concern but it's like asking the veterinarian what's wrong with your dog and not revealing whether you have a Chihuahua or a Great Dane. Plus I've discovered that many people use the generic name "pine" for any tree with skinny spiny leaves that stay attached all winter. Spruce, juniper, or pine they all have common insects and diseases but usually not the same ones. Nurseries, garden centers and your local county UI Extension office can help you with identification.
My "hurry-up-the-nurse-has-called-my-name" diagnosis for declining white pines is white pine decline. This may seem like a "hurry-up-and-make-up-a-disease-so-I-can-get-out-of-here" name but white pine decline is very real and unfortunately common.
As reported by Nancy Pataky, UI Plant Clinic director, in a recent Home, Yard and Garden Pest newsletter http://hyg.ipm.illinois.edu symptoms of white pine decline include pale, yellow or browning needles. New needles may also be stunted. White pines with decline appear yellow, pale or "off-color" and have sparse looking growth. Poor root systems have also been reported.
Unfortunately old and young white pines are affected. Often the complaint is sudden death, in as little as a month. Trees affected in the summer, when heat and drought stress is common, appear to die "almost overnight".
A baffling element to white pine decline is its appearance in an established landscape as a sudden decline of one tree in the midst of other healthy white pines when nothing obvious has changed to cause the decline. However we always have to keep in mind that even if trees are genetically similar, they are not exact replicas of each other and may have experienced different growth, planting and care.
An infectious agent has not been found as the primary cause of white pine decline. It is likely a combination of factors involving the planting site, the environment, and the species requirements. White pines are understory trees that thrive in the cool, moist, well-drained acidic soils of Wisconsin. Doesn't exactly sound like central Illinois. Many of the affected trees are planted in clay soils or exposed to the elements such as planted in new housing developments or used as windbreaks.
The planting site, how the trees were planted and the weather conditions likely contribute to decline. A combination of stresses that may cause root injury and decline include: extremes in temperature or moisture, wet or poorly drained sites, girdling roots, deep planting or mounded mulch, alkaline soil, flooding or drought stress, and possibly involvement of secondary root invading fungi.
Since the problem does not appear to be infectious, immediate removal of the still struggling white pine is not crucial. Care for white pines by watering during dry periods and mulching with 3-4 inches of wood mulch. Be sure not to mound mulch onto the tree trunk. However browning of foliage and death of branches may still occur since trees have a reduced root system. Fertilizing in spring or fall with an acidic fertilizer may also help. As Pataky states there are no pesticides suggested or warranted for this problem.
If you don't happen to catch me in the grocery store, you can bring samples along with pictures of ailing plants to your local UI Extension office. http://web.extension.illinois.edu/state Here in Champaign County our office is located at 801 North Country Fair Drive in Champaign. Or take sample to the UI Plant Clinic 1401 West St. Mary's Road Urbana 61802. plantclinic.cropsci.illinois.edu/ PH: 217-333-0519.
For information on evergreen insects and diseases http://www.urbanext.uiuc.edu/focus/index_evergreen.html