The Scourge of Spurge

By Jo Noble

Lovely to look at, caustic to hold, plant just a little --- and there goes the neighborhood.

It's spring again and, unfortunately, one of the signs that is becoming more prominent around Pine Brook is the donkey-tail spurge plant. This perennial was introduced from Europe as an ornamental plant and has shown great adaptability in our forested area. So what's the problem? Donkey-tail spurge is easy to grow. It does well in disturbed soils, on sandy slopes and rocky areas. It does so well that it can establish itself in pavement, foundations, and sidewalks. But it has no self-control and quickly escapes into the grasslands where it chokes out native grasses and flowers. If you follow the food chain, it's pretty easy to see what happens. Deer and other wild mammals won't eat it. It has no natural insect, disease or animal enemies. It attracts only a limited number of insects and perhaps butterflies. We then lose some of our bird and mammal populations, including Abert squirrels, who depend on a diverse diet including roots, fruits, seeds and the ponderosa pine tree.

The sap of the donkey-tail spurge is milky white. It is also very alkaline and can produce serious blisters if gotten on the skin. There have been reported incidents of blindness to people who have inadvertently gotten it into their eyes. It is not yet listed as a noxious weed (which has legal consequences for the property owner); but the rumor is that is soon will be. If you have donkey-tail spurge on your land, you might want to think how you will protect other people's property from becoming invaded. It can be pulled, but use protective clothing of gloves, long-sleeved shirt, and sunglasses or other eye protection. If you have questions concerning the plant, please call The Colorado Weed Management Association at 970-229-0352, or Cindy Owsley with Boulder County Open Space at 303-678-6110.

Jo Noble is a volunteer naturalist with Boulder County Open Space.

From The Pine Brook Press, Spring, 2000

Also: Myrtle Spurge Identification and Management at Colorado.gov

Dwarf Mistletoe: Not a Kissing Matter

By Jo Noble

For city dwellers, it is a holiday treat that can mortify a 12 year old boy and delight giggly young girls. For us mountain dwellers, it’s an entirely different matter. Unlike the holiday species, our local variety is a parasite that slowly sucks the life out of our pine trees. And, it is not easy to get rid of.

Dwarf mistletoe (Arceuthobium) is a gold-colored flowering plant with leafless shoots of one to five inches. During August or September, the mature seed is ejected from the plant at up to 60 miles an hour and can travel about 50 feet. The way mistletoe grows usually directs the ejected seeds upward, infecting higher branches, although it is extremely efficient at infecting trees growing nearby. The seeds are sticky and easily transported by deer, our beloved Abert squirrels, birds, etc. to other trees.

Dwarf mistletoe kills slowly, and as the tree starts to wither it becomes more susceptible to attack from pine beetles. Even though it causes more damage to forests than any other disease or insect, there has been, so far, no chemical treatment that can kill the mistletoe without killing the tree. Removal and proper disposal are our best choices. Pruning infected branches is a beginning. But because dwarf mistletoe seeds can lie dormant for several years, continuous re-inspection and further pruning is paramount.

The best protection from dwarf mistletoe is prevention. A healthy stand of Ponderosa Pine provides us with beauty, fire mitigation, and insect and disease mitigation. Pictures from the early 1900’s before logging show a healthy, more park-like Ponderosa forest with trees as much as 30 to 50 feet apart. Periodic fires would sweep through the forest, burning out small seedlings and killing invading plants, bugs and fungus. Although we certainly cannot promote this fire cycle, we can thin our trees to allow healthy stands.

If you have questions about mistletoe, bugs, disease or any other concerns, you can contact either Allen Owen or Craig Jones at the Colorado State Forest Service, Boulder District Office. For a small fee, they will come out and do an evaluation of your forested property. Their number is (303) 823-5774.

Another excellent reference is Charles Arnold’s “Homeowner’s Guide to Dwarf Mistletoe Management.” You can find it on the net at www.rmrs.nau.edu/mistletoe/hguide/.

From The Pine Brook Press, Autumn, 01