National Invasive Species Awareness Week 2018 – Japanese Knotweed

Posted on: February 26th, 2018 by Samantha Kahl

February 26th marks the beginning of National Invasive Species Awareness Week! Throughout this week, until March 2nd, we will be exploring different invasive species present within our watershed. To start off this week, we must first ask ourselves, “What is an invasive species?”. An invasive species is a species that is non-native to an ecosystem and has the potential to cause environmental harm to an area. Invasive species often out-compete native species, giving native species little chance for survival; this includes both terrestrial and aquatic plants and animals.

Japanese Knotweed within the Watershed

Japanese Knotweed within the Watershed

The first invasive species we’ll look at is Japanese Knotweed. This monster of a plant came to the U.S. as an ornamental plant in the 1800’s from Eastern Asia. Knotweed is identified by its large heart-shaped leaves, hollow bamboo-like stalks, and clusters of white or cream colored flowers. It is often found near streams or rivers and it can withstand low-light, high temperatures, drought, and poor soil quality, making this invasive resilient to many different types of environments. Knotweed can grow up to 15 feet tall, with deep rhizomes (roots) extending into the ground, making it very difficult and timely to eradicate.

Photo of Japanese Knotweed leaves & flowers courtesy of

Photo of Japanese Knotweed leaves & flowers courtesy of

Collaboration and coordination from as many people and organizations as possible is the best way to tackle Japanese Knotweed. In order to control it, one must be diligent. The Catskill Regional Invasive Species Partnership (CRISP) recommends continuous manual removal of Knotweed approximately 2-3 times each year for at least 3 years, or until it is eradicated. According to New York Invasive Species Information (NYIS), mowing or cutting of Japanese Knotweed will actually spread the plant, rather than contain it. For those who would like to use herbicides on large volumes of Knotweed, call your local CCE or Soil and Water Conservation District office to get more information on chemical regulations and safety precautions in your region.


Videos regarding Invasive Species in New York State:

Prevent the Spread of Invasive Species

Get to Know Invasive Plants


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