Spruce, Blue

This blue spruce was found on the lot of a neighborhood tree several blocks from my home. The tree was about 30' tall and had seemed healthy for the past 35 years. Yet, a year or two ago, the branches on the lower part of the tree began sagging and losing needles, which was typical of other blue spruces in the area. These samples were taken in late May.

1

This picture shows a generally healthy branch tip with green needles and almost no spores. (400x).

2

Progressing toward the base of this branch about 8", more needles are starting to lose their color in spots, and the fungal-like growth and spore density increases. (400x).

3

Here, about two feet from the branch tip, the side branches have lost about half of their needles, and the spores have significantly increased in density. (400x)

While the earlier pictures were taken in late May, the following set of pictures were taken in late September. At this time the white canker had already reproduced by shedding it's spores. Hence, there were few spores to be found.

4

Generally, as shown here, the bark surface contained only scattered light patches of white canker. (400x)

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5

Here is one piece of the bark that actually contains white canker spores, something rarely seen this time of year. However, these look like old spores, as some seem to have ruptured (yellowish stuff on them). The interesting part, however, is the hard-to-see full spore structure. It seems to begin as a yellow oval, change to a white stalk, and then to a brownish-gray tangle which gives rise to a white spore at the tip. See the red arrows. (400x)

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6

The outer bark here is heavily infested with white canker, which has probably replaced 75% of it. The phloem is also almost totally consumed by white canker. This canker has invaded a vessel (red arrow), and two fingers of canker have eaten away an area under the bark at the bottom (blue arrows). (400x)

7

While the outer bark isn't in too bad a shape here, the phloem under it has so much white canker in it that the chlorophyll is almost all gone. Of even more interest is the collection of white canker spores just outside the bark. (400x)

8

This picture could be titled "Canker Galore!", since there is so much white canker and such a variety of its forms. Most white canker seems to take the shape of a foam, reminiscent of bubble-wrap. This may be due to the canker enveloping the plant cells, digesting them, and manufacturing canker food. When the digestion process starts, the canker is gray. When it is complete it turns white to transparent. (400x)

9

This white canker has lodged itself in the bark, making it bulge out. The phloem underneath it is also riddled with white canker particles. (400x)

10

This is a photo merge of 5 needle cross-section photos taken at 400x. White canker infection is evident both near the surface of the needle and around the core of the needle. Hyphae are also present. Click the picture for a big view. (400x)

11

This is a photo merge of 6 needle cross-section photos taken at 400x. White canker infection is evident both near the surface of the needle and around the core of the needle. Hyphae are also present. Click the picture for a big view. (400x)

This blue spruce sits on a corner, with another blue spruce on either side of it. It has been in decline for the past two years, with most of the decline happening within the past year. The branch in the following two pictures has lost about half of its needles. The pictures were taken in late May.

1

If you look closely, you can see some spores, although the density is low.

2

The three needles shown above are diseased and losing color. Again, a careful examination shows some spores. There are also cobweb-like things and some brown spots on the branches.

One reason for taking these needle close-ups was to see if this (and other area) blue spruces were suffering from "needle cast" disease. If they had this disease, the needles should have had black spots along them in late winter or early spring. Earlier checks showed these spots weren't present, and there is no trace of them here. Therefore, its unlikely that needle cast is the cause of this tree decline.

This blue spruce is about a hundred feet from blue spruce #1. Over the past year or two, I had been noticing a severe decline in the health of all the blue spruce trees here in southern New Hampshire. But this one seemed immune to the decline - there were no dead needles and its branches were always held out erect. That was until mid-summer 2008, when I started noticing a sudden and dramatic decline in the health of this tree. It now resembles the others - drooping branches and dying needles. I clipped off a dying branch and put it under the microscope, with the results below.

1

Here is a picture of the lower branches of this tree where the branches are dying. The needles seemed to be exceptionally dry. The pictures below show the likely reason. (The sun was low, and at my back, so you can see my shadow as I took the picture.)

2

As you can see, the phloem and cortex are drowning in white canker. Its in the bark too. (400x).

3

It appears as if the canker growth was so extensive within the phloem that it burst through the bark. (400x).

4

The green cortex is virtually gone, and the outer phloem has lots of canker. But the interesting item here is the presence of the white canker spore on the bark. (400x).

5

The predominant brown color of the inside of this pine needle reflects the fact that it is almost dead. The outer surface is riddled with white canker and the core is half-eaten away. In the upper left corner, where the razor tore off the last bit of needle surface, the ribbon-like material is very canker-like. This is a composite picture. (400x).

6

This is a composite view of another needle only about a quarter-inch from the needle shown in the prior picture. The overall shape differs, and the center is still intact, but the outer surface is almost totally consumed with white canker. Its no wonder that this tree is undergoing serious decline. (400x).