City to use iron-based herbicide in fields this summer

When dandelion season is in full bloom, Edmonton will use an iron-based herbicide to get rid of the weeds.

Lower risk, more expensive method to get rid of dandelions

The city will spray the herbicide, iron chelate, on sports fields this summer. (John Robertson/CBC)

When dandelion season is in full bloom, Edmonton will use an iron-based herbicide to get rid of the weeds.

The city tested the herbicide's effectiveness in 2017 and has now issued a public tender to buy an estimated 48,000 litres of the product annually.

Once the city decides on a supplier it will determine which fields to target. In six to eight weeks, the city will apply iron-chelate herbicide to 60 per cent of sports fields across Edmonton, about 880 fields in total.

The herbicide will be applied up to four times over the summer. Conventional herbicides, like 2,4-D, go throughout the whole plant and require fewer applications than do iron-based products.

The city will spray iron chelate, a low-risk herbicide, on sports fields this year. The dandelions on the left have been sprayed; those on the right have not. (Lydia Neufeld/CBC)

Under the cosmetic herbicide ban, the city is restricted in what products it can apply to grass. Iron chelate is one of the exemptions. It's a lower risk way to control weeds, said Travis Kennedy, general supervisor for open space operations.

"It dries quickly, it does not have a strong odour, there's no chemical residue on the grass, it poses negligible health and environmental risks, and grass growth will not be affected," Kennedy said.

"Given the range of products that we can choose from, this is our ideal choice."

Iron-based herbicide is one of many tools the city plans to use.

"This is one piece of a full turf-management program, so our sports fields teams are out there doing all sorts of other plant health-care practices, like aeration, overseeding, fertilization," Kennedy said. "The other council direction we got was to increase our mowing cycles."

Effective, organic solution

Overall, it's about keeping turf healthy to stave off weeds, said Perry Stothart, manager of Classic Landscapes in south Edmonton.

"Turf is like us," he said. "If we have good nutrition and we are healthier, we don't get colds as often."

Iron-based herbicide is a relatively new product that Stothart called an "extremely safe" and effective method for treating dandelions without killing grass, but is generally more expensive because it's organic.

"You might get some darkening of your turf but that, pardon the pun, springs back within a few weeks and your turf looks normal again," Stothart said.

Iron-based herbicide is one of many tools the city plans to use this year to tackle dandelions. (Kaylen Small/CBC)

Other things to be aware of are hard surfaces when spraying, and the need for repeated applications every three to four weeks, to a maximum of four times a year.

Coun. Ben Henderson doesn't like the risks associated with herbicide but said going from synthetic to organic is a step up in dealing with the short-term concern.

"I'd prefer we didn't spend an awful lot of effort on the dandelions," he said. "I'm pleased we're at least not using some of the sort of more toxic product we were using before to be able to deal with it. There was more risk involved in that than was worth to essentially deal with a cosmetic problem."