Gardening: Blue Spruce struggling in Michigan yards
If you’re a tree lover like I am, you know there is something going on with many of the beautiful Colorado Blue Spruces (Picea pungens) growing in lawns across Michigan.
You won’t find these pretties growing in our forests, because they are native to the up country of the Rockies. In their native habitat they grow in fast-draining, nutrient-poor soils and once established they tend to be drought tolerant.
To begin with, in southeastern Michigan we often shove them into heavy clay soils that drain slowly and remain soggy during periods of heavy rains. Surrounded by turf that may be irrigated daily and treated with herbicides and fertilizers – chemicals that may be phytotoxic to the beautiful blues, over time they become stressed and more vulnerable to insects and disease.
One of the reasons large numbers of insects and diseases have emerged to become serious issues is the popularity of Colorado Blues in the landscape. Woody guru Michael Dirr declared this tree was “overused” in his 1980 edition of the “Manual of Woody Landscape Plants.”
Ask professionals what’s up with these beautiful blues and they may well use a collective term called “Spruce Decline” that covers a multitude of ailments.
If you have a Blue Spruce in your landscape with yellowing needles, dripping sap, oozing pitch and/or dead or dying branches at the bottom or the top of the tree, don’t think for a minute it will grow out of it if you give it a big drink of water and dose it with fertilizers. True, watering a thirsty tree is a good thing, but it won’t kill the fungal diseases or pests.
The presence of sap often indicates a canker disease caused by fungi. The most common are Phomopsis, Cytospora and Diplodia and a Colorado Blue could have more than one.
The sudden drop of last year’s needles leaving the new growth at branch tips in tact is caused by a needle cast disease, of which there are several.
And then there are the pest problems that include spider mites, Pitch Mass Borer and a host of others.
The bottom line is if you have a Blue Spruce in the landscape, keep a close watch over it for signs of trouble and if you see some, get an on-site inspection from a certified arborist, pronto.
To find a tree care professional in your area, go to tcia.org. For more information on Spruce Decline and other tree disorders go to Dave Roberts’ website at http://treedoctor.msu.edu/ Feb13_SpruceDecline.pdf.
Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. To ask her a question go to Yardener.com and click on Ask Nancy. You can also read her previous columns at detroitnewscom/homestyle.