ohmidog!

I think that I shall never see
a tree unscathed by doggie pee

                         – Not Joyce Kilmer

Maybe there are some out there — a tree or two that, in their lifetimes, have somehow avoided ever being annointed by dog.

But, sharing the country with 75 million dogs, as both trees and we do, that is unlikely — and even more so in paved-over urban areas, where dogs sometimes outnumber trees, the living things they seem to most like to pee on.

For centuries, there seems to have been an unwritten agreement — a pee-ful coexistence — between dogs and trees. But, at least for half a century or so, there have been worries expressed about the cumulative effect of the continual sprinkling that some trees undergo, especially those in densely populated urban areas.

Some were recently voiced by a Philadelphia woman with an interesting perspective. Carrie Maria owns Monster Minders, a Philadelphia dog-walking service, and she’s a graduate of the Pennsylvania Horticultural Society’s Tree Tenders program.

“Urine is highly acidic,” Maria wrote on the  The Monster Minders blog. “Simply put, dogs’ urine ‘burns’ the tree’s trunk to the point that the tree becomes susceptible to diseases, pests, dehydration and nutrient loss.”

Maria’s report drew the attention of The Atlantic, which ran a lengthy piece on its blog, Atlantic Cities, complete with photos she had taken of disfigured trees in her neighborhood she says are likely victims of pee-blight.

We can’t confirm that the damaged trees she photographed (pictured here) are solely victims of dog pee — and neither could experts. But we give her credit for speaking up for the underdog, which in this particular case is trees.

“Your dog ‘marks’ the tree, then another dog walks by 10 minutes later, smells your dog’s scent and hits it again, 15 minutes later and another dog walks by, hits it again.  This goes on day in and day out …  One dog’s scent ends up on a tree and others just keep marking it, over and over until the tree is compromised.”

Where I live — not in a real big city, not downtown — the yard in front of my apartment has huge oak trees, planted probably a good half century ago, or more. Ace pees on his favorite one regularly, but it’s so well-established it doesn’t seem to mind, and show no signs of damage.

About this time of year, the oak trees start raining acorns, and every once in a while one drops and hits Ace in the head. He jumps up and looks around, unaware he has been the victim of poetic justice.

Impervious as the big oaks in my yard may be, saplings in cities — the ones growing in a few square feet of dirt, the ones that have become potty stops for dozens of dogs daily — are another story.

“Repeated hits with urine basically causes an ‘open wound’ right on the base on the tree.  Since the bombardment from pee is semi-constant in an urban environment, the trees never have a chance to heal from past damage.  These wounds open the trees up to a slew of diseases that they just can’t fight off.” Maria wrote.

Her solution: Curb your dog.

It’s an old phrase, and one that – outside of places like New York — lots of people don’t even understand. It means to pee where the street meets the curb. And while that may lead to gutters running yellow, and car tires taking on a pee-scent, thereby attracting more to dogs to take aim on them, Maria finds that preferable to the tree assault.

“It’s simple.  Redirect your dog when he/she is headed for a tree,” Maria says. ”Teach your dog to ‘curb it.’”

How big a factor is dog pee, compared to all the other hazards urban trees face — like road salt, car doors, poor soil, limited room to grow and youths with pen knives? As the Atlantic Cities blog points out, experts aren’t sure:

“Whether pee hurts trees is a question that’s attracted virtually no research attention since its earliest mention in the academic literature …”

The post mentions one presentation, way back in 1959, in which a plant pathologist named Pascal Pirone warned of the dangers. In ‘Why shade trees die along city streets,’ a presentation given at the International Shade Tree Conference, he said ‘dog canker’ could kill trees up to 6 inches in diameter.”

But the Atlantic post also quoted a staff member at the Smithsonian Institution’s horticulture department as saying the trunk damage shown in Maria’s photos could have come from a number of causes, “including mechanical damage [i.e. mowers, car doors, pedestrians], southwest injury, disease [cankers], and insects [borers].”

While the extent of the harm caused by dog urine remains untallied, most experts agree it can’t be helping trees.

“We deal with it in the sense that I imagine trees get added stress or maybe anxiety” from dogs, says John Thomas, associate director at Washington, D.C.’s Urban Forestry Administration. “I don’t know how much dog urine you need to kill a tree. But there’s definitely something there…. Somebody could definitely get a masters or Ph.D. out of studying it.”

(Photos: Top photo by John Woestendiek; tree photos by Carrie Maria / Monster Minders)