Weed Resistance

Weed Resistance 

I recently watched the Vice report “Saviour Seeds” on GMO cropping (On HBO Season 3 Episode 9), during the program they talked to some farmers from Paraguay on their experiences with growing Roundup Ready soy beans. Their main issue with the product was the issue of weeds resistance that they stated was caused by the excessive use of  glyphosate (The herbicide commonly referred to as Roundup). Personally I thought that the story was servilely one sided and heavily bias but even so weed resistance is unfortunately a real everyday issue for many farmers around the world including Australian farmers.

But are GMO crops to blame?.

In short the answer is NO, while in some countries it could be argued that the misuse of glyphosate in Roundup Ready crops has helped to increase the prevalence of weed resistance it is unfortunately a problem that affects many areas in Australia and around world including those that have never been touched by GM cropping. So what causes herbicide resistance?

Herbicide resistance occurs when a plant a natural mutation in the plant allows it to become immune to the mode of action (the bit that kills the weed) in a herbicide. If the the same herbicide is applied in further sprays this plant may then survive allowing it to set seed, leaving viable seed in the soil for up to 10 years. Resistant plants then germinate from the seeds and if a chemical with the same mode of action is used these plants will set seed and possibly spread. The situation can then be made worst if the producer changes to chemical with another mode of action using it religiously until the weed becomes resistant to it as well. The situation is now that bad in some parts of Western Australia that weeds are resistant to several modes of action almost eliminating chemical options.

In order to combat this issue the producers have had to adopt Integrated Weed Management (IWM) strategies in order to help manage and reduce the problem. Common features in many IWM strategies include rotating modes of action, the double knock strategy and non chemical control methods.

Rotating modes of action involves using different types of chemicals that will still kill the weeds but will use a different method in order to prevent a resistance occurring to one type of mode of action. The different mode of actions can be determined by checking the label to see its group.

The double knock strategy is similar to rotating modes of action and involves making at least two passes over a field. The first pass is down with a chemical using one mode of action before a second pass is done with another chemical that uses a different mode of action in order to knock out any weeds that may of been left by the first pass. This method is becoming increasingly popular when used in conjunction with WeedSeeker technology that identifies weeds in a paddock and only sprays them instead of doing a blanket spray over the entire paddock. This has caused a massive reduction in the amount of chemical used on farm and the operating cost allowing many more expensive chemicals from different groups to be a cost effective option.

Finally the last control method is the non-chemical mechanical control which can take many forms from the simple to the more elaborate. Strategic ploughing is one of mechanical options available as it is able to physically destroy the plant in the fallowed paddock working under the simple idea that no weed can develop resistance to steel. Other methods include trying to control the seed bank though using machinery like seed crushers that a pulled behind the harvester to windrowing stubble in a way that allows it to be burned destroying any seeds.

Overall weed resistance is a problem that effects the entire cropping industry and not some accidental by-product of a RoundUp ready cropping system, it is also a problem that can be managed, prevented and avoided through care full management. I’d like to finish this discussion on Weed Resistance by asking two questions on the Vice program.

1. VICE News​ claims that farmers could use a range of herbicides before the introduction of RoundUp Ready (RR) soy beans in order to prevent and control resistance. But before RR soy beans you couldn’t spray any herbicide in crop and could therefore only spray during fallow. So why aren’t they still rotating their herbicides during fallow to control and prevent resistant weeds along with weeds in general while using glyphosate to control weeds in crop as recomended?

2. If the Paraguay’s farmers are so unhappy with the product why do they still use it and not revert back to conventional seed? The program stated that the majority of Paraguay’s farmers used RR soy beans but not all farmers do meaning there are still conventional seeds on the market, so why not switch back?

On a side note…….

The show also commented on how the how the UN has recently found glyphosate to be “probably carcinogenic” which in all fairness they have. But in this day and age everything seems to cause cancer so I thought I’d research things that are proven to cause cancer and are not just “probably carcinogenic”. According the American Cancer Institute there are many many things that can and will cause cancer however I have chosen to just list a few everyday materials that are Group 1: Carcinogenic to humans such as:

  • Alcohol (I know, I was disappointed as well)
  • Coal
  • Tar
  • Engine exhaust
  • Leather Dust
  • Mineral oils
  • Salted fish
  • The Sun (Solar/UV Radiation)
  • Soot
  • Wood Dust
  • Tobacco/Tobacco Smoke

 

Just to lighten things up here’s a song that a South Australian agronomist and farmer wrote about weed resistance and is called the Wild Radish Song.

Advertisements

One thought on “Weed Resistance

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s