Pesticide, herbicide, fungicide: all of these words incite horror in our crunchy-granola, nature-loving hearts. For good reason, many of us are opposed to the use of man-made chemicals against plants and insects. For example, DDT (dichloro-diphenyl-trichloroethane) is a pesticide that was invented in the 1940s to combat insect-borne zoonotic diseases. It is also widely used to protect crops against damage by insects. We are unsure of its harm to humans, but we do know that it has great environmental impacts because of its adverse effects on organisms. This is the case with many insecticides and herbicides-- small, "unharmful" amounts of chemicals may be added to the ecosystem, but they build up in organisms throughout the trophic levels as they become concentrated in their fatty tissues. This process is called biomagnification.
Improper use of chemicals in the environment has caused massive die-offs of fish, insects, amphibians, reptiles, birds, and mammals. They also seep into our groundwater and can spread to other bodies of water many miles away from their source.
But what do we do about invasive plants, which are just as harmful to our ecosystem health? Of course there are many alternatives to controlling invasives: digging, pulling, burning, smothering, solarizing, girdling, and biocontrol. All of these methods come with their own costs and benefits, but the biggest issue conservation managers face is time and money. With the right team of people and resources, invasive plants can be manually controlled. However, while Libby, Marjorie, and I spend hours and hours every week pulling goutweed at the Intervale Center and implementing different control methods, we continuously ask ourselves "is this worth it?". The answer is YES, if our methods are effective and implementable on a large scale. Let's say that smothering a 10x10' plot of goutweed successfully kills off all of the roots in one patch. All the goutweed is dug out of the patch and then a black tarp is put down to kill off the root system. Surrounding goutweed is kept out of the patch by planting a perimeter of native ferns around it. The patch is then rehabilitated with native trees, shrubs, and herbs. Is this a success story, even if it works? It depends on who you ask, but I believe that the method needs to be much more efficient if the invasive covers hundreds of acres of a parcel of land.
Even though I pride myself on being a left-leaning gal who preaches about environmentalism, I now fantasize about using herbicides to combat certain invasives. However, I am not totally ready to abandon my morals. Instead, I am ready to put down my shovel and put on my thinking hat so my back can take a break. If we can find a way to responsibly apply an herbicide that causes little to no long-term damage to the environment, then I'd say we go for it.
Marjorie has found success with eradicating weeds with a simple solution of vinegar, salt, and clove oil. This solution is far less harmful than other herbicides, but it is less aggressive and is non-selective about which plants it kills. We sprayed this natural herbicide on a patch of goutweed at the Ethan Allen Homestead; this patch is also scattered with stinging nettle, but we aren't too worried because nettle is a very abundant species so this trial should not cause any harm to the local population. We will continue to monitor and spray this plot with the herbicide throughout the summer, noting any effects on surrounding plant species and soil chemistry. This vinegar solution may not be the solution to our goutweed problem, but it's worth a shot. Goutweed control will likely take many more years of research, trial, and error, but hopefully with time and dedication we can provide some useful insight.
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