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


Fol­low us this week as we uncover more inva­sive species in our Ashokan Water­shed! Face­bookTwit­terInsta­gram




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