When The Land Conservancy acquired South Branch Preserve in 2010, there were 12 fields that were being actively farmed, and one small field that was fallow and had not been farmed since 1990. The approximately 4 acre field was early successional and already overgrown with invasive shrubs.
In 2015, The Land Conservancy’s Stewardship Manager, Dennis Briede, observed some small spots of Mile-a-minute weed (Persicaria perfoliata) in this area of the Preserve. These were sprayed with herbicide. The area being fallow and overgrown impeded detailed observation until Mile-a-minute emerged atop shrubs, despite the initial attempt to treat it. Within two years it was clear that this appropriately named invasive vine had overtaken the entire field.
The Land Conservancy was determined to find a non-chemical method of eradicating this invasive plant due to the extent of the invasion and the proximity to the South Branch of the Raritan River. After some careful research we developed a plan to proceed with dual bio-controls. First, we set up Project Chew, in partnership with Antler Ridge Wildlife Sanctuary. We acquired the necessary equipment and installed livestock fencing and a run-in shed. Once we had the site prepared, Antler Ridge delivered the “Chew Crew,” consisting of 5 goats and 3 sheep. The Chew Crew then spent the entire season working the field and happily munching away at the Mile-a-minute weed, which they love, as well as other invasive plants and shrubbery throughout the four acre area. The Chew Crew will continue this work each season for five years, which is how long Mile-a-minute seeds remain active in the soil. A critical component of the success of this bio-control is making sure the plants are grazed heavily enough during each growing season, to prevent the plants from dropping new seeds.
At the same time, we reached out to the Bureau of Biological Control at New Jersey’s Department of Agriculture, and requested their assistance. The Bureau has been extremely helpful and Bureau Chief Mark Mayer visited South Branch Preserve and deployed our second bio-control. The Mile-a-minute Weevil (Rhinoncomimus latipes) was imported to the US from China in 2004, following approval by USDA and extensive testing showing that it feeds and reproduces only on Mile-a-minute weed and is not likely to have any negative direct or in-direct effects in North America. Approximately 1,000 weevils were released at South Branch Preserve courtesy of the Bureau of Biological Control. We are extremely pleased to find the weevil doing its work at the Preserve, as shown in the photo above. The mile-a-minute invasion at South Branch Preserve will continue to be closely monitored and we are confident that over time, the dual bio-controls will help us to diminish and hopefully eradicate this invasive plant from our Preserve.