Garden Q&A: Blue spruce in Maryland won't be long lived

For The Baltimore Sun

Our blue spruce is losing its needles, and I've witnessed other evergreens in the neighborhood dying. I'm afraid it is also what will happen to our tree. Lower branches are dying from the inside (near trunk) out to the tips. Only the top one-third looks green, lush and healthy. Also, white sap is coming out of the trunk.

Everywhere you go in this area, you will see cytospora canker taking out blue spruce. Though very popular in the past, (Colorado) blue spruce are not well suited to most of Maryland, as they are native to cooler climates. They typically look good for 20 years or so, then drought stress makes them susceptible to fungal attack. Cytospora is the most common fungi, yet about 80 percent of blue spruce simultaneously have Rhizosphaera needlecast. There is not much you can do other than water during dry periods. Pruning out severely infected or dead branches can slow disease spread. Prune during dry weather. Blue spruce is a tree that should be enjoyed for a while with the knowledge that it will not live long. Consider replanting with a Maryland native. Search cytospora and Rhyzosphaeria in the HGIC website.

I read that plastic mulch is good for stopping weeds, but on the other hand, I learned plant roots need oxygen. Plastic does not let air get to the soil. Also, water must get under the plastic. So how does this work?

In general, vegetable beds are about 2 to 4 feet wide and oxygen gets to the roots without being an issue. You can place drip irrigation under plastic mulch or cut holes in it with scissors when planting seed or transplants and water at the base of the plants. You need not use drip irrigation. Plastic mulch generally lasts for one season. A good commercial grade landscape fabric (weed barrier) is water permeable and can last for many seasons without sun protection.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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