Monday, November 22, 2010

Mistletoe

"The mistletoe is still hung up in farm-houses and kitchens at Christmas, and the young men have the privilege of kissing the girls under it, plucking each time a berry from the bush. When the berries are all plucked the privilege ceases."

--Washington Irving, The Sketch Book of Geoffrey Crayon, Gent., 1820

What a charming custom that is, and yet in our house mistletoe doesn’t engender friendly feelings of that sort. Maybe it’s because we have too much of it, year round, to the point where it’s about to bring another of our trees to its knees.

Mistletoe is a parasitic plant that grows on a wide range of trees, its roots invading the bark to extract water and nutrients from the tree. Usually the host doesn’t die because the mistletoe would die with it. However, some trees, like our Bradford pear (Pyrus calleryana 'Bradford') get weakened to the point where limbs start to break off. Since this poses considerable danger to anything or anybody near the tree, the only solution is to remove it. This is what happened last year to a Bradford pear in our front yard.

The mistletoe infestation on the second Bradford pear in our front yard has gotten much worse this year, to the point where it, too, will most likely have to be cut down. Since this is a City tree, a defined procedure has to be followed. We’ve started the process but it can take a quite a while before a decision is made. Fortunately, all work will be done by the City at no expense to us.

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The large green clump in the photo above is mistletoe
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Another large clump of mistletoe
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Here you can clearly see the point where the mistletoe is attached to the tree
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A branch with berries. The berries are eaten by birds which in turn pass the seeds in their droppings. When seeds deposited on tree branches begin to sprout, their roots penetrate the tree bark.
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Almost ripe berries
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The leaves are fleshy, reminiscent of succulents

When our neighborhood was built in 1989/1990, Bradford pears were apparently the street trees de jour because every other house on our street seems to have, or have had, one. Many have been removed over the years because they became brittle and split in the middle; of the remaining ones, more than 90% are infested with mistletoe to some degree. I think it’s just a matter of time before they will all have to go. My hope is that cities have learned about diversification and not longer populate entire neighborhoods with just a couple of different tree species.

For more information about mistletoe, check out the University of California pest management web site.

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