Colorado and Norway Spruce have been among the most popular evergreen trees used in the landscape throughout the mid-west and beyond. Unfortunately, these spruces are subject to a wide range of insect and disease problems that can impact their growth and their aesthetic appeal.
The prevalence of certain pests has intensified over the years leading to more rapid decline of these spruce trees. Increasing spread of canker diseases along with aggressive insect infestations continue to plague our beautiful spruces.
Key Spruce Tree Diseases:
Needlecasts
The name speaks for itself as infected trees shed needles. As the disease progresses, the needles die, usually the year following the initial infection. In time the tree looks much thinner on the inside losing its lush full appearance. The greater the infection the weaker the tree becomes and therefore decline continues until death. There are 2 common types of Needlecasts found in the spruce. The first is called Rhizosphaera and the other is called Stigmina/Mycosphaerella.
Tip Blights
There are certain tip blight diseases to be aware of which are more deadly than others. Phomopsis tip blight is an aggressive disease and yet one of the most misdiagnosed ones we deal with. Tip blight diseases infect the growing ends of branches causing the tips to die. Repeated attacks from tip blight leads to premature needle loss and can become so severe that it results in significant decline and eventually total death.
Canker Diseases
Canker diseases are caused by fungi that infect branches or the main stem (trunk). Cankers interfere with the branches ability to transport nutrients and water resulting in the death of branches. Cytospera Canker is an aggressive canker disease usually killing branches from the bottom up. This disease is often mistaken for Phomopsis tip blight. This misdiagnosis is a problem as treatments for Phomopsis and Cytospera are not all together the same.
Key Spruce Tree Harmful Insect/Mites
Spruce spider mite
This true mite (not in the actual insect family) is often found breeding and feeding in numerous species of spruce trees. Once the female is comfortably settled on any spruce tree, the female begins creating offspring, which quickly turn into thousands and thousands of mites now sucking the life out of the fresh new tender growth. Without warning (or so it seems) these mites soon cause discoloring of the needles, needle drop occurs, once healthy, happy limbs begin to sag and soon the tree is now fighting for its life. Spruce Spider Mite can be found active all throughout the growing season and once an outbreak is detected a series of treatments may be needed to provide managed eradication and or managed control. The one thing to know is root fertilizing spruce trees in the spring actually promotes spider mite activity. It is a better practice to root fertilize spruce trees in the fall if at all possible.
Spruce Scale
This tiny, white covered insect lives on both old and new needle growth. While Spruce scale is a lesser concern in most spruce if left alone, these insects (similar to the Spruce Spider Mite) multiply quickly and by the hundreds if not thousands. Simply put, this insect can suck the life out of the tree to a point where the tree is beyond care or recovery.
Pitch Mass Borer
This insect threat is more often found in pine trees. However since the early two thousands this insect has and is a more viable threat to Norway and Colorado spruces. This insect also creates clogs in the trees vascular system thus restricting needed nutrients and water. Pitch Mass Borer can become very aggressive in the damage it causes to the spruce. It has a long and complicated life cycle thus requiring a intensive plan by way of controlling this borer.
Zimmerman Pine Moth
Ever see yellowish, pink like color pitches of mass oozing from your spruce? Could be your tree is under attack from Zimmerman Pine Moth. One of the early symptoms often seen is the top candle (highest point of the tree) is dead while the rest of the tree appears to still be normal and healthy. Don't be tricked thinking your tree is going to be ok, it's not. Once you see this symptom you can rest assure your tree is under attack and needs care sooner than later.
So... What Is Wrong With My Spruce?
As you can see from the threats mentioned in this article (and there are many more not mentioned here), while we all desire healthy, happy and picture ready spruce, there's always a threat just waiting to change your vision and desires. One treatment method or chemical doesn't work for everything. And some treatments are more cultural than chemical. Some options may include trunk penetrating sprays, others may need outer branch spray coverage. Then there are some infestations which can only be treated by way of either macro or micro root flare or trunk injections. Some treatments offer 2 year care while others require a multitude of timely services.
Root feeding is very important to meet the goals of sustaining healthy spruce. Pruning and disinfecting as needed is a practice well worth the investment. Correct mulching under the tree and good drainage is also very impactive.
As you can see it's not a one size fits all solution when it comes to caring for your spruce trees (even if the neighbor appears to have the same issues it may not be true). Before making any plan of action, the first thing everyone should do is consult with a professional arborist ensuring correct diagnosis as we can create a solid plan of action and services that will both meet your mission and your vision for your spruce trees.
Not sure what's going on with your spruce trees? That's why we're here, we help people care for their trees! Call us today and schedule a free no obligation visit with one of our highly trained arborist.