Foul-smelling ginkgo seeds wreak havoc after city plants female tree in error

When the borough of Saint-Léonard planted a ginkgo tree on Dino Delisi's lawn, he liked the distinctive, fan-shaped leaves and its bright yellow colour in the fall.

But his early admiration for the tree is long gone.

About five years ago, he noticed what looked like gumball-sized fruit growing on the branches and each season, the crop has increased.

Turns out, the borough planted a female tree by mistake.

In the fall, the seeds, which resemble yellow cherries, fall to the ground and the fleshy exterior turns into a mushy, putrid ooze. The smell can be overpowering, described by some as akin to rancid butter, but for Delisi, he says, "it's more vomit and rotten fruit mixed together."

If he's cutting the lawn or raking the seeds up, Delisi finds it hard not to gag from the stink.

"Whenever I finish raking, I have to come in, take my shoes off, go downstairs and wash them with a brush or else that smell just stays on the shoe," he said.

Neighbours give home a wide berth

Delisi has watched people cross the street to avoid the smelly, slippery mush on the sidewalk in front of his home. He's also warned people with dogs to steer clear, because the seed contains a toxin that can make them sick.

The seeds eat away at his lawn, creating tiny craters of dead grass if he doesn't remove them quickly. He estimates he's spent about $2,000 to repair the damage.

When it's cold, Delisi rakes the seeds onto the sidewalk. A few years ago, the borough sent a front-end loader to scoop them up, but Delisi says they haven't been back since.

"I told the city guy, look at my age, I'm retired. I'm not going to rake fruits every day. I'm not a farmer. If I wanted to buy a farm, I would have bought a farm," said Delisi, 68. "He says, 'Yeah, but our workers are not allowed to go on your lawn.'"

He's repeatedly pleaded with authorities to replace the ginkgo with another tree, but the city won't budge because the tree is healthy.

Ginkgo well-suited for cities

Native to China, the tree's seeds or nuts are enjoyed as a seasonal treat in many Asian cultures.

An extract from the tree's leaves is also used in several medicinal products.

In North American cities, the ginkgo tree is a popular planting choice because of its tolerance to cold weather, pollution, road salt and insects.

"It's pretty much a bulletproof tree," said David Wees, a faculty lecturer in McGill university's department of plant science and associate director of the farm management and technology program.

The downside — the female trees are extraordinarily smelly.

The ginkgo's seed pods release butyric acid when they begin to rot or are crushed.

Butyric acid can be found in other stinky things such as parmesan cheese and body odour.

Typically, cities don't have issues with the ginkgo tree as long as male trees, which only produce pollen, are planted.

But it can be difficult to distinguish between male and female trees because the female trees don't begin to produce seeds until 15 to 20 years after they are planted.

To avoid accidentally planting female trees, Wees says a lot of municipalities and landscapers only plant certain clones of ginkgo that are propagated from stem cuttings of a male plant.

"You're basically genetically reproducing the same plant over and over again and then you are sure it's going to be a male plant," said Wees.

However, horticulturalist Celia Aceae says there is evidence to suggest ginkgo trees can change sexes.

"There have been cases recorded where male trees have actually started to bear female branches," said Aceae. "If there are no females around, this is the reaction the tree has."

Both Aceae and Wees understand it's not easy to pull out a mature tree, but are surprised the city won't replace it — especially if they have received so many complaints from Delisi and are spending money to send a front-end loader to clean up the mess.

Stinkiness not a valid reason to fell tree

A couple of years ago, Delisi says the borough sent staff to prune his ginkgo tree's branches and he was assured it would reduce the amount of fruit.

But Delisi says this year was the worst it's ever been and he's worried about what will happen as the tree gets bigger.

"My lawn is full, but once it gets a little bigger, those fruits are going to start falling on my roof and into my eavestroughs," said Delisi. "There's no end to it."

Dominic Perri, a city councillor for the Saint-Léonard-Ouest district, says the borough plants over 1,000 new trees a year to combat climate change.

Although the smell emanating from Delisi's tree is disagreeable, it's not considered a justifiable reason to cut it down and replace it.

"Only trees infected by pests, trees deemed dangerous by a professional and trees with at least 50 per cent of dead branches are cut down if pruning can't save the tree," said Perri, referencing a city bylaw.

An email from the Saint-Léonard borough says there are nearly 100 female ginkgo trees in the area, the result of a "mistake" by the nursery in the past, as only male gingkos are planted now.

The borough says it's working with the city's parks service to see if there's a way to reduce the smell and if picking the fruit before it falls would reduce the odour.

Delisi suggested putting a net under the tree to catch the falling seeds, but the city said no.

He's fed up and wants the tree removed but was warned by the city he could be fined up to $15,000 and possible jail time if he removed it himself.

"Nobody should have a tree like this," said Delisi. "It's ridiculous."