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September 23, 2018

Herbicides To Be Used Against Invading Water Chestnuts


OSWEGO – Starting next week, herbicide will be used to help eradicate water chestnut growth in parts of the Oswego River.

Water chestnuts are an invasive weed that grows on the surface of the water on several CNY rivers.

The application will be performed by a boat like this one.

The application will be performed by a boat like this one.

These plants create an obstacle to boaters and prevent swimming in many areas along local rivers.

The Oswego River has long been infested with these weeds and the Oswego County Soil and Water Department is working to eradicate this invasive species, according to John Dehollander, of the Oswego County Soil and Water Conservation District.

The two primary methods of controlling this plant are hand-pulling them before their seeds drop or applying an aquatic herbicide to kill the plant.

The Oswego County Soil and Water Conservation District has hired Allen Chase Enterprises Inc. to perform a herbicide application on several areas of the Oswego River in Oswego County.

These applications will be performed on August 29 and 30 in the area of Ox Creek and Big Island south of the city of Fulton.

This shows the amount of water chestnut infestation at Route 48 in Ox Creek a couple of years ago.

This shows the amount of water chestnut infestation at Route 48 in Ox Creek a couple of years ago.

“There shouldn’t be any problems. We have sprayed the Oswego River and Ox Creek for many years now,” Dehollander told Oswego County Today. “There have been no issues of concern or side effects. Understanding the restrictions that do come along with the particular chemical being used is important for you to understand.”

Water samples will be taken to determine when chemical concentrations are low enough to lift the restriction, he said, adding that this usually only takes less than a week after treatment.

Riparian owners will be notified when restriction is lifted.

“The chemical used is a direct-contact spray, meaning that it is targeted only to the water chestnut plants,” Dehollander said. “Some incidental neighboring plants may also get sprayed and killed. Most generally, these other plants are also of an invasive type, i.e. Eurasian milfoil.”

No fish kills have ever come about due to the spraying of water chestnut, he pointed out.

Mature nutlets

Mature nutlets

The chemical actually becomes inert quite quickly should it hit water or soil, Dehollander explained.

“Usually, within one week the restrictions can be lifted, if conditions allow. I had a crew of five interns for 10 weeks doing water chestnut hand-pulling in 18 different sites throughout Oswego County. It still is a problem in our waterways and if private people do not engage themselves in controlling for invasive species, they will just get away from us and government can not do it all! A vigilant effort needs to continue,” according to Dehollander.

Chase Enterprises addressed the following to those who may be impacted by the spraying:

Dear Riparian Owner:

As contracted by the Oswego County Soil and Water Conservation District, Allen Chase Enterprises Inc. will be applying the herbicide Clearcast to control the excessive growth of water chestnut.

The treatment is for approximately 50 acres of water chestnut in Ox Creek near the Conrail tracks and 20 acres in the Oswego River near Big Island.

The work is scheduled to take place Monday August 29, 2016 and Tuesday August 30, 2016.

You are being notified because your land is along the shore and within a ½ mile from where the control effort will be performed, as stipulated by the state’s permit conditions.

The use of treated water will be restricted or prohibited as follows:

• Do not use to irrigate greenhouses, nurseries or hydroponics until imazamox concentration less or equal to 1pbb.
• Within a quarter mile of a water intake Clearcast applications cannot exceed 50ppb.
• Do not use Clearcast treated water in a concentration greater than 50pbb for irrigation until residue levels are less than 50ppb.
• Do not plant sugar beets, onions, potatoes or non-Clearfield canola in soils that have been previously irrigated with Clearcast treated water until a soil bioassay successfully demonstrates acceptable levels of crop tolerance.

This notice is required by the New York State Department of Environmental Conservation.

Sincerely,
Allen Chase
President

About Water Chestnuts

Cat Hadlow with water chestnuts she pulled at the Battle Island area of the Oswego River and Canal during a volunteer effort a few years back.

Cat Hadlow with water chestnuts she pulled at the Battle Island area of the Oswego River and Canal during a volunteer effort a few years back.

Floating leaves are triangular to rhombic in shape, one to two inches long, and have sharp pointed teeth on the margins.

They are arranged in a broad rosette that sits on the water surface.

The submerged leaves are alternate and coarsely feather-like, growing up to six inches in length.

Tiny white flowers emerge from the center of the rosettes and produce large (about one inch) hard, horned fruits.

Fruits ripen in about a month and soon sink to the bottom.

Most fruits germinate within the first two years, although a few may wait up to 12 years.

One seed can give rise to 10 to 15 rosettes, and each rosette may produce as many as 20 seeds. With high rates of germination, growth can be explosive.

Decomposition of the large volume of plants may also contribute to lower levels of dissolved oxygen in shallower waters.

Low levels of oxygen adversely affect the natural inhabitants of these waters, creating additional problems.

Previously, control of the plant was attempted by the Oswego County Soil and Water Conservation District with a weed harvester used to cut the surface pads before the nuts were ready to split open, killing the plant.

Also, volunteer groups have done early-season hand-pulling of the plant where small quantities were forming.

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