In recent years, Edmonton’s sports fields have been overrun with dandelions, and now the problem has become so bad that the city is stepping in to battle back the noxious weed.

In the next few weeks the city will begin assessing its 1,465 sports fields, and doing two applications of a herbicide where needed.

“At a high level we are estimating that 60 per cent will need action,” acting director for NE district park operations Travis Kennedy said. “If more than 60 per cent do need action, we’ll address those as well.”

READ MORE: City mulls spraying Edmonton parks and fields because of dandelion ‘perfect storm’

The city said since it stopped spraying its sports fields with conventional herbicides two years ago, many have become overwhelmed by dandelions and other broadleaf weeds.

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Seeds deposited each year have taken root, and healthy growing conditions this year mean the number of weeds is exceeding the city’s acceptable levels.

The City of Edmonton will spray sports fields. The weed on the left has been sprayed. Vinesh Pratap, Global News

What herbicide will the city be using?

In waging war against the weed, the city has selected a product you probably have in your garage. The technical name is iron chelate, but it goes by an eco-sense brand name like “Weed-Be-Gone,” among others.

READ MORE: Dandelions dominate lawns as Edmontonians demand more help from city

Doug Jones, deputy city manager for operations, said iron chelate is five times more expensive than the conventional 2-4-D-type herbicides banned by a 2015 city council policy preventing the use of herbicides for aesthetic purposes.

“It’s not cheap,” Jones said.

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“In order to do the sports fields themselves it’s going to cost about $750,000.” Tweet This

That’s about ten per cent of the city’s annual budget for all lawn mowing, trimming and other maintenance. Jones said the department will absorb this cost for the rest of the year, and in August will bring a report to city council to talk about the budget for future years.

A field full of dandelions in Edmonton June 12, 2017. Global News

Sports fields will remain the priority — meaning medians, parks and other locations won’t be treated. Jones estimated that if the city used iron chelate on everything it would cost $10-million. “It’s a big ticket item.”

The average cost of the product, per treatment per field, is about $250.

Is iron chelate safe?

Iron chelate is one of the lowest-risk options available, according to the city, and will be applied in a way to both “maximize effectiveness and minimize exposure.”

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Iron chelate blocks the way the weed absorbs oxygen. The city said the herbicide will cause dandelion plants to turn a black or dark reddish-black colour and shrivel up within about a day. It might make some grass a darker green colour, but is not unsafe.

A City of Edmonton truck arrives to spray a park for dandelions on June 16, 2017. Scott Johnston/630 CHED

Health Canada has listed it as having low toxicity and minimal environmental impact meaning it’s safe for kids and pets. “Once it dries in ten of fifteen minutes, they’re back on it,” Jones said.

READ MORE: Dandelions: Beastly bane or beautiful bounty?

When will the fields be sprayed?

Two treatments will happen this summer once school is out. The first will start in late June and continue through July. The second treatment will be applied a few weeks later.

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Jones said they’ll avoid spraying in mornings because dew will leave the product wet longer. The city said fields should be avoided during spraying but will be safe to use after drying, between 30 minutes and three hours after application, depending on weather. Signs will be posted when the fields are being sprayed.

The plan is for city staff to then to come in later and aerate, over seed and fertilize to restore the fields to a stronger condition.

Another reason the city wants to wait a couple of weeks: staff doesn’t have a lot of product on hand right now, and needs to get a shipment in from Toronto.