“My spruce tree has brown things all over it! Is it sick?” The caller was quite anxious. He had a beautiful Colorado Blue Spruce growing in his yard, and now it had some sort of weird alien growths at the ends of all the branches. Was it going to die?
Over the years that I volunteered at the master gardener help desk, we would often get calls like this. No, the caller’s tree wasn’t sick, not exactly. Those prickly, cucumber-shaped growths that show up on spruces from time to time are actually galls caused by an insect. They might look peculiar, but they weren’t going to cause significant harm to his spruce.
Colorado has a love affair with the blue spruce (Picea pungens). Perhaps we’re enamored with the striking, steel-blue tint to the needles, and the way the color causes fall’s orange leaves to glow. Perhaps we appreciate the towering, pyramidal shape of a mature tree, or the short and squat dimensions of a dwarf cultivar.
A number of gardeners I’ve talked to added a blue spruce to their yard because it’s Colorado’s state tree. Blue spruces may not be the easiest species for Front Range landscapes, but they’re definitely worth the effort.
We all know that deciduous trees—oaks, maples, and the like—lose their leaves in the fall. But what about conifers? They’re supposed to be evergreen! Should we be worried if we see lots of brown needles on our pines and firs?
As is frequently the case with questions about gardening, the answer is “it depends.”
Mistletoe is a holiday tradition. We decorate our doorways with it, where tarrying under a spring might bring you a kiss. Unfortunately, the kind of mistletoe growing along Colorado’s Front Range isn’t so romantic. Five different species of dwarf mistletoe infest pines, spruces and firs. Given enough time, an infected tree will eventually die.
All mistletoes are flowering plants that have given up a life of self-sufficiency to become harmful parasites. Dwarf mistletoes lack leaves, so they have little ability to make their own food from sunlight. Instead of extending their roots into the soil, they have root-like structures that penetrate under the bark, where they siphon off both water and nutrients from the host tree.
The female mistletoe plant produces sticky seeds. When the seed capsules are ripe, usually in late summer, they explode, expelling their contents at speeds up to 60 mph! The seeds can travel up to 60 feet, although 30 feet is more common. Wherever the seeds hit, there they stick.