Disease, bugs sapping life out of area spruce trees

Kyla Smith
The Detroit News

The deciding factor for Josh Leo to move into his home three years ago, was the row of 40-foot tall spruce trees that lined the driveway and backyard.

Josh Leo sits at the bottom of a Colorado Spruce tree, where the limbs have died. Leo's spruce trees have been infected with the rhizosphaera needle cast disease at his Davisburg home.

“It’s a pretty cool setting once you see it. That’s why we bought our home,” the Davisburg resident said. “The trees also give us privacy. It would be pretty catastrophic to lose them.”

Native to the Rocky Mountain region, Colorado blue spruce, green spruce, white spruce and blue spruce trees are very common in the Midwest. But for the past two years, the popular trees are disappearing across the state and researchers are stumped as to why.

“Spruce decline is a very complex story,” said Dr. David Roberts, academic specialist at Michigan State University. “People love the trees for their appearance and the steady growth rate, but because it’s not natural to our environment, they are more susceptible to diseases and insects.”

Roberts said the three types of diseases — needlecast, canker disease and tip blight — along with two types of insects — Gall adelgids and Spruce spider mites — are credited with the decline in spruce trees.

While there is no cure, Roberts said there are treatments that can slow down the progression of the disease.

Josh Leo walks along diseased Colorado Spuce trees. Leo's spruce trees have been infected with the rhizosphaera needle cast disease at his Davisburg home.

Dave Bargerstock, district manager for The Davey Tree Expert and a certified arborist, said these diseases are not new.

“What we have noticed is that the trees are dying at a fast, alarming rate,” he said. What’s affecting the trees “appears to be a complex hybrid of diseases with a combination of a fungus and insects or mites that’s attacking the tree at once.”

In the past year, Bargerstock said his company has treated more than 2,000 infected trees, which is unusually high.

“This is reminiscent of the emerald ash borer disease a few years ago,” he said. “So many of the trees were planted, so when the insect was done with one, they could just go to the next house until eventually the entire neighborhood or community of trees were wiped out.”

The emerald ash borer is an invasive species believed to have arrived in the Detroit area from China in wooden pallets or packing crates. It was first discovered in Michigan in 2002 and has spread throughout the upper Midwest and killed about 50 million ash trees.

The purple limb of a White Spruce is the first sign of the disease. Leo's spruce trees have been infected with the rhizosphaera needle cast disease at his Davisburg home. It begins at the bottom of the tree and works up.

When it comes to spruce trees, homeowners need to know what to look for:

Needlecast: Symptoms of a tree attacked by needlecast fungi Rhizosphaera is needles shedding from the bottom up, turning a hint of purple and eventually dying.

Canker diseases: This infects the branches or the main stem of the tree. Symptoms include sunken areas along the stem that my drip with resin. The canker inhibits the tree from transporting water and nutrients causing each branch to die individually resulting in the death of the entire tree.

Tip Blight: The fungal disease causes dieback to new shoots on the tree and commonly affects pines and spruces.

Gall adelgids: The tiny insects eat the shoots of the plant sucking the sap, causing the shoots to deform.

Spider mites: Insects cause needle discoloration, killing them.

Bargerstock does not advise homeowners to start a treatment program without having an arborist examine the tree.

“This is something that you can’t treat with regular pesticides,” he said. “Sometimes a person will use insecticide hoping it will kill the spider mites, but that is not the case. Usually, the tree can be managed after symptoms are identified, but in worst case situations, the tree will need to be removed.”

The estimated cost to treat an infected tree can run between $400 and $500 annually, and up to $1,000 for larger trees, Bargerstock said.

So far, researchers are looking at preventive treatments, but some arborists say it could be close to five years before a cure is found.

As for Leo, an arborist comes to his home in early spring, summer and fall, to take care of his diseased Colorado blue spruce trees.

“Unfortunately, I know that these treatments will be an ongoing process. These are not trees that you can just replace. It takes years and years from them to grow as they are today,” he said. “But, if this will protect them, then it will be worth it in the end.”