Some Weed Problems Introduction

Giant Hogweed (Heracleum mantegazzianum) by Walter J. Pilsak

We know and love (or, more commonly, hate) weeds for their ability to spread to and cover bare soil exposed by fires, floods, plows, and garden spades. Like band-aids on skinned knees, weeds protect soil from erosion by wind and water. This is good, and should be good enough for us to be selective (not stereotyping) in our attitude toward weeds. But it isn’t. The reason for our persistent hatred is that weeds can compete with and replace crop and garden plants, they can replace native vegetation, and they can block vision and even travel. And, as you will see in the first article below, some weeds have toxic chemicals for defense and aggression and can inflict serious injury to grazers or innocent passersby.

Giant Hogweed (by Appaloosa)

People used to use the techniques of organic gardening to prevent and eradicate weeds. However, in the middle of the last century, science gave us herbicides, chemicals that interfere with weed growth and reproduction. What a pleasure to wave our spray wand over weeds and watch them shrivel and die. For decades, agricultural scientists have improved herbicides. They have even paired them with genetically modified crop plants that aren’t hurt by the magic spray that kills invading weeds.

Herbicides disrupt nature and cause cancer in humans. The chemical industry claims that reduced cost of food production justifies herbicide use. However, herbicides are growing stronger and farmers are applying them more heavily. This increases the harm to nature and human health.

Weeds are not defenseless against herbicides. Most of them produce seeds for the next generation in a single year, and this allows natural selection of herbicide-resistant plants within a few years. As described in the second article below, weed resistance is exceeding the power of the herbicides. As the gap between herbicide efficacy and weed resistance grows, farmers will return to the old organic gardening techniques. Though this will be less harmful to nature and people, it will increase the cost of farmed produce. Consequently, we may have to reduce meat production, a major consumer of farm crops, and, eventually, we will have to reduce human population size.

The articles below include recent discussions of weed problems.

Some Weed Problems References

• O’Kane, Caitlin. June 18, 2018. Giant hogweed, plant that causes blindness and third-degree burns, discovered in Virginia. CBS News.
• Borel, Brooke. June 18, 2018. Weeds Are Winning in the War against Herbicide Resistance, Herbicides are under evolutionary threat. Can modern agriculture find a new way to fight back? Scientific American.
• International Survey of Herbicide Resistant Weeds.

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