Weed management: Exploring sustainable, conventional and organic options

Food choices can be confusing — from organic to local to GMOs, how do consumers decide what’s best for them and their families?

Organic foods are frequently depicted as the “better” option compared to non-organic crops which may be treated with herbicides and other products.

This classification often leads consumers to believe that organic crops are produced using only safer and sustainable methods, but that’s not necessarily the case.

Based on my experience in the field and the classroom, I’d like to share some insights on how herbicides fit into safe and sustainable farming practices.

Control Methods

I think it’s fairly common for people to believe organic produce is synonymous with harmless and even pesticide-free. The truth is, organic weed control methods can actually be quite extreme and unsafe.

For example, one form of organic weed management is torching weeds with propane, which wouldn’t be my idea of the safest or most environmentally friendly weed control practice.

Vinegar, used at high concentrations of 25% or 30%, is another organic weed control technique for spraying weeds.

These high levels of vinegar are so caustic and corrosive that warning labels must be displayed on the delivery trucks transporting these chemicals and spray applicators are required to wear safety goggles and rubber gloves and they are advised to avoid inhaling the concentrated vinegar mist due to respiratory hazards.

Organic weed control can also use electric weed zappers, which are like tasers for emerged weeds. The zapper hits the weed and grounds energy down into the soil.

This heats up the water in the plant and kills the plant cells, releasing steam and an enormous amount of energy.

Having a mobile lightning rod move through the field is an obvious safety concern, but the other downfall is the electricity generated using a tractor that is burning diesel fuel while creating enough electricity that could have powered 20 houses.

Herbicides get a bad rap so it’s important to understand how chemicals are actually helping us move toward greater sustainability.

As a weed scientist, I believe soil is one of our most precious resources and herbicides help us maintain soil conservation by reducing the need for tillage to uproot weeds.

These tillage practices reduce soil stability and alter the soil health profile, while adding to greenhouse gas emissions from the fuel being burned to power the tillage operations and the release of carbon from the degradation of soil organic matter.

We’ve already experienced the Dust Bowl disaster nearly a century ago because of overreliance on tillage and yet tillage is one of the primary practices that is increased for weed control when some farmers transition from conventional crop production to organic.

Greater sustainability comes from using as many tools as possible to manage weeds while protecting the land — no-till practices, cover crops, crop rotation and, yes, even pesticides.

A key to this diversified approach is using a balance of tools instead of focusing too much on any one practice.

Prior to the 1900s, weed management was all organic because synthetic herbicides didn’t yet exist. However, these practices were not sustainable and the use of modern herbicides was deemed necessary for weed management.

Targeted Applications

It’s amazing how far we’ve come with technology when it comes to herbicide applications — and pesticides, in general.

An exciting innovation is sprayers with computer vision to selectively apply herbicides only to weeds while avoiding application to the crop.

I’ve tested this type of spray system in our field research program and the technology has the potential to reduce pesticide use in crop fields, increasing a farmer’s profitability while reducing the potential environmental impact of spraying herbicides.

Two key differences in the synthetic, selective herbicides used in conventional crops and the herbicides used for organic crop production are:

• Conventional herbicides tend to persist longer in plants and soils to extend the completeness or duration of weed control.

• Herbicides used in organic culture can be just as injurious to crop plants as weeds.

The short-term and nonselective — in other words, injury to crop plants — impact of organic herbicides on weeds necessitates more frequent application to manage new flushes of weeds throughout the cropping season while increasing the risk of crop damage from misapplication.

All farmers have a unique set of circumstances that influence the specific production practices they implement on their farms, whether that be an organic, conventional, or GMO production systems.

As with all farmers, those using conventional practices care deeply about preserving the land and using herbicides responsibly — we are all stewards of the land, after all.

The more you get to know about their practices, the more you’ll realize that all crop production systems require compromise and conventional systems allow for more tools in our perpetual battle against weeds.

Bryan Young is a professor of weed science at Purdue University.