Dreaded Canker Disease

Hello Fellow Readers, Hector and Judy of Morristown NJ, longtime clients become friends, have a “Big and Little” vignette of blue spruces that have begun to decline. Their little blue looks as though the needles were stripped from the lower branches. “Did the deer do this to my baby blue spruce,” asked Judy? I wish it were the deer as the problem would be easier to manage. (Spruces remain highest in deer resistance.) Their “Big and Little” have the dreaded canker disease which is killing off stands of spruces.

Judy and Hector’s “Big and Little” Blue Spruces

Penn State Extension Office reports both blue and Norway spruce are susceptible to the branch killing disease, though in our area blue spruce seem most impacted. Its caused by the fungus cytospora kunzei. Trees over fifteen years old are most often infected though younger trees can also contract the slow-moving disease.

The treetops look healthy, but the lower branches have died

You’ll first notice a reddish to brownish cast on branches leading to browning of the needles which eventually fall off. It typically starts from the lower limbs and makes it’s way up. You may notice yellowish-brown, purplish-white, or white patches of resin on the bark.

When weakened or stressed, as with all living things, trees become more susceptible to disease. Both too much water and drought can stress spruces. We’ve had consecutive seasons of drought which no doubt has added to the devastation. Be sure of proper irrigation and that the soil drains well. Deep root fertilization is recommended to stimulate growth to help fight canker disease. Fertilizing may also encourage new growth in the smaller naked areas, but rarely will large dead areas fill back in. Cut off the diseased branches to the nearest healthy lateral branch or the trunk. Only prune when the tree is dry as wetness will encourage the spores to spread. Sadly fungicides are ineffective as the fungus infects wounded tissue but can remain dormant with no symptoms and therefore fungicides cannot be successfully timed.

One of my pet peeves is lower branches cut off evergreen trees which look as bad as wearing knee-high pantyhose with a short skirt. There were three mature beefy blues on our property I adored that were infected with canker disease. Despite a top “don’t” desperate measures sometimes overrule. I kept the three beauties going for a handful of years by limbing up the unsightly branches and planting Bottlebrush Buckeye below to fill in the gnarly trees knees. About the time the Aesculus parviflora grew to be head high, it was the time to cut down the poor blue spruces. Still, it was hard to destroy trees whose tops seemed healthy. Sometimes you just must let things go. But never wear knee-high pantyhose with a short skirt. Garden Dilemmas? AskMaryStone@gmail.com

Both Blue and Norway Spruce can be infected with canker disease

How canker disease spreads: The fungus enters through wounds that can remain dormant until the tree becomes stressed. Then small cankers form with thousands of spores though they are hard to see. When the diseased tree becomes wet, the spores ooze out in yellowish strands that splash spores onto other branches.

Judy wrote: I’m “feeling very Hollywood to be featured in your article.” To which I responded, “You are Hollywood. Here you are carrying your bouquet on the red carpet. You look so “glam.”  

Judy is making use of her Smoke Bush trimmings/ Cotinus coggygria ‘Royal Purple.’

My former Christmas tree, a Norway Spruce, with early stages of canker disease.

Update: My Norway Spruce is back to health! Thanks to Neem Oil :^)