Reaping what we sow
 
Chemical titans say they have what farmers need to fight superweeds, but will they only be adding to a growing problem? Ian MacLeod reports
 
By Ian MacLeod, Ottawa Citizen May 12, 2012
 
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It all started innocently enough seven or eight years back, recalls Philip Shaw, a farmer near Dresden.

Preparing to plant a field of soybeans one day on his 350 hectares in the heart of southwest Ontario, he puzzled over what was later confirmed to be a brand new breed of mutant weed, one of the very first in Canada.

The species was a common Giant Ragweed, but this particular Ambrosia trifid L. refused to surrender to Shaw's repeated assaults with the reliable old herbicide glyphosate.

The darn weed was practically indestructible and, with some hardy cohorts, would eventually grow back and ruin his soybeans.

Glyphosate was introduced by farming and chemical colossus Monsanto in 1974 under the brand name Roundup. It soon became the world's No. 1 broad-spectrum weed killer.

Two decades later, the company ushered in the age of genetic farming in 1996 with Roundup Ready soybeans, genetically modified to tolerate the spraying of glyphosate. Roundup Ready alfalfa, corn, cot-ton, spring canola, sugarbeets and winter canola followed.

It was the dawn of the "Roundup revolution," a rosy new age in crop agriculture. Crop yields climbed and production costs fell. Roundup Ready was universally hailed and began dominating much of North American's farming landscape.

But some tried-and-true farming practices were left behind in the ensuing dust.

Many farmers, especially Americans, employed straight glyphosate, instead of rotating herbicides to lessen the potential of developing weed resistance. Others planted the same crops in the same fields year after year. Some didn't rotate their fields or their herbicides.

Eventually, the science of natural selection took root. Individual weeds fit enough to withstand glyphosate survived the sprayings and reproduced, again and again and again. Fields were overrun.

Weed resistance to one particular herbicide is not new. But so many farmers' misguided dependence on a single, miracle product left millions of hectares of North American farmland vulnerable.

Sure enough, farming now has a nasty new adversary.

In the U.S., about a dozen species of "superweeds" such as pigweed are immune to glyphosate and have invaded almost five million hectares of southern and Midwest farmland.

Two superweed species - Giant Ragweed and Canada Fleabane - have been confirmed at 125 sites in southwest Ontario and a third - Kochia - was recently confirmed at three sites in southern Alberta, where an enormous acreage of Roundup Ready canola is one of the country's prime crops.

"We're seeing more sites and they're found over a wider geographic area," says Peter Sikkema, a leading expert on agricultural weed management at the University of Guelph.

"The cattle have already left the barn (but) I do think that through proper weed management, we can delay or reduce the (natural) selection for additional glyphosate-resistant weeds," in Canada.

"The reality is, if growers don't control these weeds, they're going to have reduced yields and increased costs."

A single Canada Fleabane produces 10,000 to one million seeds, depending on its growing environment. A really strong wind can potentially blow those babies into the next county.

Shaw, for example, had never grown Roundup Ready soybeans or corn, and only sprayed glyphosate sparingly for weed "burn downs" to prepare his fields for seeding.

"However, I have Roundup weeds. That's what I have a problem with," he says. "If your neighbour has it -. then suddenly you've got the problem."

And what a problem. "If Giant Ragweed gets really bad, it will completely shade out the soybeans underneath it and you'll get up to 93 per cent yield loss," he says.

Enter Enlist, a proposed weed management system by Monsanto rival Dow AgroSciences.

If approved by Canadian and U.S. regulators, corn and soybean seeds genetically modified to withstand combined sprayings of 2,4-D choline and glyphosate will begin to go on sale in Canada and the U.S. next year.

"Without new technology, the glyphosate-tolerant cropping system is going to be facing some very serious problems," says Garry Hamlin, a Dow spokesman in the U.S.

"Glyphosate resistance has been a sobering experience for growers. There are folks in the south who are (now) spending $100 an acre to hand weed their crop. Glyphosate has been a significant benefit to farmers, perhaps the greatest revolution in farming in their lifetime and they don't want to lose that technology."

Dow is confident Canadian farmers will embrace Enlist.

"They realize how serious the issue is in the U.S. and unless something's done here, we'll be in the same situation," says Dr. Allan McFadden, a Dow Agro-Sciences research scientist in Guelph.

Monsanto, meanwhile, has a new genetically modified soybean line in the regulatory approval pipeline that is tolerant to the herbicide dicamba as well as glyphosate. Like 2,4-D, dicamba is another decades-old herbicide and synthetic auxin that mimics natural auxin hormones regulating plant growth. Treated weeds quickly outgrow their source of nutrients, wither and die.

If approved, what is now known only as MON-87708 is expected to see a limited launch in Canada for the 2014 growing season.

Monsanto and Dow officials agree Roundup Ready will remain commercially viable, while Monsanto bristles at the suggestion its product is to blame for the spectre of superweeds.

"It's more the misuse of glyphosate, or the inappropriate use of glyphosate, or the single reliance on glyphosate as your weed control tool over and over and over again on the same field," says Trish Jordan, public and industry affairs director for Monsanto Canada.

Pesticides, she adds, are misunderstood by many people, "who don't understand the importance pesticides play in agriculture.

"For whatever reason, people that get concerned about this, or hyped up about this, or maybe just downright scared, just don't understand the amount of regulatory oversight that goes into these products and that pesticides serve a useful purpose."

Enlist and MON-87708 face considerable opposition in the U.S. because of their reliance on 2,4-D and dicamba.

A coalition of U.S. farm interests led by fruit and vegetable growers and processors is demanding federal regulators reject approvals for the proposed products over several concerns, including their claim that 2,4-D use will increase manyfold.

Separately, the Save Our Crops Coalition wants the Environmental Protection Agency to investigate herbicide spray drift, which it says could kill and injure fruits and sensitive vegetables kilometres away.

While older formulations of 2,4-D can evaporate off target plants and drift as a vapour to non-target plants, Dow insists its 2,4-D choline formulation reduces spray drift and volatility by 90 per cent.

"Our goal is entirely consistent with the Save our Crops Coalition's concerns," says Hamlin. We "don't want to see off target movement either. We believe that reasonable people can work together to resolve their differences and we're certainly willing to do that."

Ontario's fruit and vegetable growers take a wait-and-see attitude.

"If you manage it right, I don't expect to see much of a problem," says Craig Hunter, an expert adviser on crop protection and pesticides for the Ontario Fruit and Vegetable Growers Association.

Commercial growers in Ontario require formal training and provincial certification every five years in the handling of pesticides, including glyphosate, 2,4-D and dicamba.

"The days of reckless abandon from 40 years ago are dead and buried," says Hunter, though he still advises growers of sensitive crops, "to have a serious discussion with your neighbours - (to find out) where these materials might be used, just to be on the safe side."

Enlist's 2,4-D choline also is raising predictable health and safety concerns with some critics, despite being the most thoroughly investigated chemical on the planet.

Health Canada, the World Health Organization, the U.S. Environmental Protection Agency, the European Commission and others say there is no conclusive evidence 2,4-D causes cancer or genetic mutations when used as directed.

Yet respected medical bodies continue to cast doubt.

An influential 2004 study for the Ontario College of Family Physicians, for example, analysed about 250 previously published epidemiological studies on possible adverse effects of pesticides on human health and concluded "consistent positive associations" between pesticides, including 2,4-D, and cancers, reproductive problems, neurotoxic effects and other serious illnesses.

What's not so clear is whether pesticides alone are responsible, or whether they're just another toxic straw in the heap of chemicals on humanity's back.

The Ontario government jumped into the debate in 2009, banning cosmetic use of pesticides, including 2,4-D, dicamba and glyphosate, on lawns, gardens, school yards and parks. Some other provinces have followed.