Garlic mustard (source: Katja Schulz)

When I was younger, my dad, my sister, and I would often volunteer at the local botanic garden, where we ripped out and chopped up invasive plants like garlic mustard and common buckthorn. This was not easy work, particularly for an eight year old and a five year old.

Invasive plants like the ones my family helped remove have led to the decline of 42% of endangered and threatened species in the U.S.

These plants are so damaging because they do not have natural predators in their new environment. This means they are able to reproduce and spread without any obstacles. This also means people need to continuously remove these plants. Garlic mustard, for example, comes back annually. That patch we spent hours weeding? It was likely back to full strength in just a year.

Had I known this, eight-year-old me might wonder if there’s a way to make sure volunteer days actually keep invasive species from growing back.

Recent research by Maarten B. Eppinga and colleagues reveals exactly that: a better way to weed. 

Using a model and a case study on coral vine (Antigonon leptopus), researchers examined seven different types of patches to focus on removing, such as random patch removal, removal of the smallest patches, or removal of the largest patches.

The study revealed a plant’s reproduction process affected the success of removal strategies. If a plant reproduces asexually (without another plant), certain strategies work better than if the plant reproduces sexually (with another plant). For instance, removing random patches of asexually reproducing plants kept them from spreading but removing random patches of sexually reproducing plants was not as successful.

Using this information, volunteer day planners or anyone else removing invasives can strategically pick which areas of plants to remove. 

Normally people might think targeting the largest patches would be most effective, but, according to Eppinga’s study, the opposite is true. Concentrating on the largest patches is actually least successful at controlling a species’ spread.

Instead of going big, planners could focus on smaller patches of sexually reproducing species or random patches of asexually reproducing species.

Such smart weeding strategies can not only eradicate more species, they can also free up time and supplies. With more time, little kids like my eight-year-old self could be exploring the botanic gardens rather than weeding them. More importantly, though, these newly found resources can be devoted to removing one of the other 4,300 invasive species found in the United States, which, all together, cost $120 billion on average per year in damages.