Hydrilla Management: Tips On Controlling Hydrilla Weeds

Hydrilla Management: Tips On Controlling Hydrilla Weeds

By: Bonnie L. Grant, Certified Urban Agriculturist

Hydrilla is an invasive aquatic weed. Controlling hydrilla weeds is necessary to prevent the diminishment of native flora. In most states, it is illegal to possess or transport the species. The plant grows rapidly, spreads easily, and out-competes native vegetation. It also fouls waterways with its thick tangled mats of stems. The plant is a federally listed noxious weed. Read on to learn more.

What is Hydrilla?

Hydrilla management is the responsibility of pond and lake denizens. What is hydrilla? The plant is often confused with our native Elodea, but it has one or more teeth on the underside of the midrib. This gives the plant a rough feel when you drag your hand down the length of the stem.

The plant is native to Africa, Australia, and parts of Asia but has managed to take over many areas of our native flora here in the U.S. The plant is of greatest concern in the southern states but has managed to migrate in small populations to the western regions. It has also been discovered in some northern and Midwest regions.

Identification is the first step to eradication. Hydrilla is a perennial plant with dense mats of stems that grow in water over 20 feet (6 m.) in depth. Stems are snaky and numerous, floating in a tangle on the surface of the water. Leaves are narrow with some serration, 1/8 to 3/8 inch (0.5 to 1 cm.) long and have spines on the underside of the midrib.

This plant reproduces by seed which is carried on the water but also by fragmentation. Any tiny bit of the plant that is broken off has the capacity to become another plant. In areas with aquatic recreation, plants are consistently torn up to perpetuate the problem.

One positive note of hydrilla plant information is its contribution as a habitat for fish and animals. Initially, the plant has beneficial effects on fishing areas but, over time, the low oxygen levels in the mats do not support the growth of local animals.

How to Kill Hydrilla

Aquatic and wildlife managers have discovered how difficult hydrilla management can be. This is because of its ease of spread and reproduction. Controlling hydrilla weeds is an issue of concern in most of the United States and has become an economic problem in some regions.

As early as the 1980s, $49 million was spent on hydrilla management. The numbers have since increased until infestations have become a budgetary burden in those localities with the highest populations of the plant. It is now known that cold tolerance is another aspect of hydrilla plant information, a detail that makes management even more challenging.

Methods of Controlling Hydrilla Weeds

Dredging and hand pulling or trawling are not effective strategies. This is because of the ease with which the plant establishes itself from small fragments. Stem fragments with only one node can form roots and shoots in just a couple of days.

Physical control such as lowering water levels, adding aquatic dye, or covering the surface of the water to reduce light has minimal effect. Drained ponds may respond to granular herbicides applied to the mud to eliminate tubers.

Grass carp have been introduced in some areas and are efficient at eating and removing some of the plants.

Chemical control is the most effective but cannot be used where there is drinking water. Copper, when mixed with other herbicides, is a useful tool but care must be used around fish.

Other chemicals include diquat, endothall, fluridone, and dichlobenil. Each of these has extensive hazards and should be applied by a professional or by use of approved formulas recommended for aquatic management. Apply all cautions and respect the instructions regarding application methods and rates completely.

This article was last updated on

Debate rages about how to control spread of hydrilla in lakes


For more than 60 years, an evolutionary super plant has flourished in Florida’s fresh waters.

It’s helped fishermen make big catches and decreased fish mortality rates. It’s given duck hunters clear shots.

But it’s also choked out boat motors and overrun waterways, making some nearly unnavigable.

Like it or not, hydrilla has become a part of Florida’s ecosystem.

Today, Lake County is home to the state’s costliest hydrilla infestation. This year’s legislative funding to control it has run out with four months still left in the state’s fiscal year, leaving officials concerned about the future of our lakes.

Adding to the concern: The Florida Fish and Wildlife Conservation Commission late last month put a temporary statewide moratorium on spraying herbicides amid environmental concerns. The agency is now holding public meetings to gauge the public’s views on chemical control.

Meanwhile, hydrilla continues to grow on the Harris Chain of Lakes.

Some worry that, if left untreated, the invasive plant could devastate the county’s 100-plus lakes and the tourism dollars associated with them. Others say overtreatment would do the same thing.

In the early 1950s, an aquatic plant dealer dumped bundles of Indian star vine, originally from Sri Lanka, into a canal behind his business in Tampa.

By the 60s, infestations had been reported in various bodies of water including Crystal River, Snapper Creek and Lake Osborne. In 1969, two scientists identified the mystery aquarium plant — it was hydrilla.

Today, the FWC oversees aquatic plant management.

According to its position statement on hydrilla, it "can adversely impact native plant abundance, sportfish growth, recreational use, flood control, and dissolved oxygen." But the FWC also "recognizes that in water bodies where native submersed aquatic plants are absent or limited, hydrilla at low to moderate densities can be beneficial to fish and wildlife."

Last year, the agency spent $10 million treating hydrilla across the state.

Knowing what scientists know now, it’s no surprise hydrilla has taken over Florida’s freshwater bodies.

It grows and reproduces quickly and in any freshwater body and bodies of water with low salinity.

Boaters can fragment it, too, and inadvertently spread hydrilla to other bodies of water. After a recent fishing tournament on Lake Harris, hydrilla littered the shores of Ski Beach.

It also needs very little light, another trait that contributes to its proliferation. The invasive “wakes up” and starts photosynthesizing earlier than native aquatic plants, said Jason Ferrell, professor and director of the University of Florida/IFAS Center for Aquatic and Invasive Plants.

“It’s already jumping on it and getting ahead of them,” he said. “It’s just a dirty little competitor.”

And even when it doesn’t get much light, it finds a way, Ferrell added.

For instance, Lake Harris is a pretty “green lake,” he explained. The amount of algae in it can block hydrilla in deep water from getting its necessary sunlight, but only for so long.

Behind Long Island on Lake Harris, a thick patch of hydrilla has nearly reached the water’s surface in water deeper than 10 feet.

It wasn’t that tall a couple months ago.

“It’s kind of scary it’s all the way out here now,” said Mike Perry, executive director of the Lake County Water Authority.

So how did a plant that took root in nearly 11 feet of water grow to the top?

Hydrilla can actually suck nutrients — including algae — out of the water, essentially purifying it to get light to itself.

“Now it’s getting more light down to the bottom,” Ferrell said. “As soon as the light hits it, it jumps and then jumps again, almost like a forest fire.”

A forest fire: That’s an accurate simile to describe how hydrilla has spread in Lake County over the past 18 months.

When Hurricane Irma struck in September 2017, it made treatments ineffective.

Herbicides normally stay to their targeted area, but with so much extra water in the system, they couldn’t.

That had a snowball effect on treatments, and FWC has been playing catch-up since.

Lifelong Leesburg resident and recreational boater Shayne Toler said he’s never seen hydrilla so bad.

“It seems like it’s just growing out of control and it’s going to overtake the lakes,” he said.

Pro bass fisherman Tim Frederick isn’t concerned about that. He said hydrilla levels are perfect.

“I’m happy with it. I think it’s great right now,” he said. “Not one time has it impeded me.”

FWC funding to fight hydrilla comes down through the Florida Legislature. The 40 state senators and 120 representatives approve a budget every year, which includes money that goes to the FWC.

Over the past 20 years, the FWC has spent $19.8 million in Lake County in its efforts to control hydrilla.

It’s a big number, but two counties got more.

The FWC has spent more than $104 million to control hydrilla in Osceola County since 1997, and more than $37 million in Polk.

But in recent years, Lake County’s problem has grown.

Between the 1997-98 and 2002-03 fiscal years, the state spent less than 1 percent of its annual hydrilla control expenditures in Lake County.

In the 2003-04 budget, Lake got 4.25 percent of the FWC’s hydrilla funding.

The county’s share went up and down — sometimes dramatically — from there. During the 2017-18 fiscal year, 43 percent of all state funds spent on hydrilla was used in Lake County.

In total, the state treated hydrilla in more than 20,600 acres to the tune of more than $10 million. Lake County got $4.3 million of it. Most of that — $3 million — was spent on treatments in Lake Harris.

The state spent more money last year controlling hydrilla on Lake Harris than any other lake in the state. Lake Tohopekaliga in Osceola County was No. 2, at $1.7 million.

“The Harris Chain is the most expensive to treat because those lakes are some of the deepest in the state,” said Carli Segelson, an FWC spokeswoman.

Treating an acre of shallow water, depending on the chemical used, can run $400 to $600, Segelson said. For deep water, it could cost between $1,000 and $1,300.

This year, the FWC initially earmarked about $1.5 million to control hydrilla in the county. They added another $700,000 to supplement that, pulling from other projects around the state.

That money is already gone. And the 2018-19 fiscal year doesn’t end until June 30.

“Hydrilla doesn’t stop growing even if there’s no money,” Perry said.

Funds ran out because Lake County “has had (a) much higher need than we’ve expected based on historical information,” Segelson said.

During the Lake County Delegation meeting last month, Lake County Commission Chairwoman Leslie Campione and Amy Stone, Lake County Water Authority board chairwoman, asked local legislators to support more funding for the county’s hydrilla problem.

As it stands, the FWC has about $7.3 million left to treat hydrilla all over the state in this year’s aquatic plant management budget, Segelson said. The agency has requests for more treatment totaling $8.8 million.

For its part, the Water Authority raised its millage rate last year because of the hydrilla problem. It has set aside $1.5 million in its 2018-19 budget to supplement FWC funding.

But for now, the board is respecting FWC’s spraying moratorium, Perry said.

On the board’s meeting budget next week, however, is an item that would authorize the Water Authority to use funds to help control hydrilla.

The FWC paused spraying late last month. At the heart of the moratorium are environmental concerns.

“The FWC has been receiving feedback both in favor and not in favor of aquatic herbicide treatment and we think now is a good time to take a temporary pause and collect public comment,” Segelson said. “The recently announced meetings build on the FWC’s long history of engaging the public to provide feedback on this process. These meetings will provide the public with an opportunity to provide their opinions and thoughts about management activities on Florida water bodies.”

So far the FWC has held four stakeholder meetings. The agency is holding two more in Lake County this week. The first starts at 5:30 p.m. Monday at the Astor Community Center. And the Eustis Community Center is hosting a meeting Tuesday, which also starts at 5:30 p.m.

At the first three meetings, in Kissimimee, Okeechobee and Sebring, almost 500 people showed up. The commission also received more than 500 emails on the subject.

FWC staff briefed the seven-member commission on these listening sessions at its meeting on Thursday in Gainesville.

Kipp Frohlich, director of FWC’s division of Habitat and Species Conservation, told the commission that overwhelmingly, people prefer non-chemical control methods over herbicides, citing environmental concerns.

“All things being equal, most people would say, ‘don’t put chemicals in the water, remove the plants,’” Frohlich told commissioners.

Before an herbicide is used in Florida’s waters, it goes through EPA and Florida Department of Agriculture and Consumer testing processes.

First, the EPA gives them an OK, but then the state comes in and does its own analyses.

Seventeen active ingredients are approved by both agencies for herbicidal treatments in Florida’s waters.

State officials say these chemicals are safe they have to go through two rounds of testing, after all.

However, they do recognize that pouring chemicals into Florida’s water bodies just doesn’t look good.

“Seeing chemicals go into our awesome waterways is a hard visual for me, for anybody,” Frohlich told FWC commissioners.

Some say it’s more than just bad optics.

Marine life expert Jim Abernethy started a Change.org petition six months ago urging the state to stop using chemicals to kill hydrilla, citing carcinogenic potential in the approved herbicide glyphosate. It has since gotten more than 174,000 signatures.

Frederick, the pro angler who is sponsored by Lake County, has concerns about chemicals’ effects on bass fry and babies.

Fry gather in hydrilla stalks to protect themselves from predators. Spraying fry with herbicides is like spraying a human baby with a mosquito repellent, Frederick said.

“That’s just not the time to do that,” he said. “You can’t tell me it’s not killing them.”

And after a spray, the dead plants just fall to the bottom, contributing to bottom muck.

One alternative is mechanical harvesting. In these processes, specialized boats actually pull up aquatic weeds.

That, too, has its drawbacks.

First, it’s a bit more expensive. An acre of hydrilla that costs $1,056 to treat chemically would cost $1,907 to mechanically harvest, the FWC said.

But the costs of mechanical harvesting may soon decrease. Frohlich said the FWC already is in talks with harvesting companies to bring the price down.

Still, the process can unintentionally pull up fish, turtles and other native wildlife. Plus, it can fragment the plant even more, leading to new growth.

There’s also not much use for hydrilla. Since it’s 95 percent water by weight, Ferrell said, it dries up within minutes of being out of the water.

Some eat hydrilla, which is calcium rich and high in B12. But it is illegal to take hydrilla in Florida without a permit and it’s on the federal government’s noxious weeds list.

The state has also used sterile grass carp to help control hydrilla. But that’s not a perfect solution either.

Grass carp eat hydrilla, and just about everything else. They’re indiscriminate eaters and also feast on native Florida aquatic plants.

And if a few batches of carp are released in a chain of lakes, like the Harris Chain, they could convene in one lake and decimate its ecosystem.

So hydrilla’s invasive. It’s quick growing. And it’s expensive to control.

Why not just eradicate it?

“If you asked 10 people about hydrilla, you’re going to get eight different answers,” said Jean-Paul Galbreath, a recreational boater in Leesburg.

That may be an understatement.

Kayakers aren’t huge fans because hydrilla can be hard to paddle through.

It can also block access to waterfront homes and businesses.

Ducks love to munch on hydrilla, so duck hunters like a topped out patch here and there.

Bass fishermen like Frederick love hydrilla for a few reasons.

It’s good for fish mortality rates. Because hydrilla gives fry a safe place to live, the bass population is up.

“The fishing is three times better here than it ever has been,” Frederick said.

Because the plant filters water for its own benefit, water is clearer. Some parts of the Harris Chain, like Emeralda Marsh, are “crystal clear,” he said.

In his role with the county, Frederick also recruits fishing tournaments to the area. They’re a huge source of tourism dollars — one tournament can have a $1.5 million economic impact.

“Hydrilla, even though it’s an invasive, is probably the best thing to happen to our lakes in Florida,” Frederick said.

Not everyone sees it that way. Many are concerned too much hydrilla could have a negative effect on the county’s ability to draw in other recreational lake users.

It’s overheated the motors of boaters like John Mayfield. It’s happened to him on many occasions.

“You have to stay put for a half hour sometimes for the motor to cool down enough for it to crank up and go again,” Mayfield said.

He’s also caught patches of hydrilla with the keel of his sailboat.

“You can’t even move when that happens,” Mayfield said.

Toler has watched boats get caught in hydrilla patches near his mother’s waterfront home in Sunnyside.

“They’ll drive out in that stuff and get bogged down and have a hell of a time getting back out of it,” he said.

It’s the FWC’s job to take stakeholder feedback and implement plans for individual bodies of water.

“The question is: How do we manage this in a way to try to satisfy all these groups?” Ferrell said. “That is what FWC is struggling with.”

The agency’s local biologist, Nathalie Visscher, gets calls almost every day from stakeholders, Segelson said.

And that’s not a local phenomenon.

The pause on spraying continues.

FWC board of commissioners didn’t lift it at its meeting, but directed staff to move forward with improvements to the state’s Aquatic Plant Management Plan, recognizing the process is still far from over.

At the end of Thursday’s standing room-only FWC meeting, they had heard from more than 40 stakeholders, many talking about Lake Okeechobee or the Kissimmee Chain of Lakes.

They detailed the decline of their bodies of water, sometimes loudly. No matter the lake, the stories were similar. Vibrant bodies of water with submerged vegetation and impressive fish populations now look, feel and smell dead because of the chemicals the FWC uses to kill aquatic plants.

From Lake County, however, was Perry.

He told the commission that the Water Authority supports the FWC’s use of herbicides, and that for the Harris Chain, it’s the only viable option to control hydrilla.

He told them the state funding is gone to treat hydrilla, and that the Water Authority has set aside money to treat, and are ready to use it to supplement FWC’s work.

“And then along came the pause,” Perry said. “We understand the importance and the need for doing the pause. While the pause goes on, hydrilla continues to grow.”

"Please, if you need to continue the pause in order to change the way you manage Lake Okeechobee or Kissimmee or anything to the south, please feel free to do that,” he said. “But please restart the herbicide treatments in the Harris Chain… Let’s not let a $2 million problem that we have now turn into a $10 (million) or $20 million problem in the future.”

Controlling Hydrilla In The Croton River: Plan for 2019

    Lanning Taliaferro , Patch Staff

Hydrilla is an invasive plant able to kill US river ecosystems. (NYS DEC)

CROTON-ON-HUDSON, NY — Join Croton officials and the NYS Dept. of Environmental Conservation Tuesday as they discuss this year's plan to control hydrilla in the Croton River.

Hydrilla is native to Australia, Asia and Africa and is believed to have made its way to the U.S. as an aquarium plant. It grows and spreads rapidly and is one of the most difficult aquatic invasive plants to control and eradicate in the United States. Its dense mats of vegetation can interfere with boating, swimming, and fishing, as well as severe consequences for aquatic ecosystems.

Hydrilla is often spread by boaters, as hydrilla fragments can cling to boats and trailers. Very small fragments of hydrilla can start new populations.

It was discovered in the Croton River in 2013. The state treated the infestation in 2017 and 2018 by putting the aquatic herbicide Sonar Genesis, also known as fluridone, into the river just below the New Croton Dam and at Black Rock Park.

The meeting will start at 7:30 p.m. Tuesday in the Georgianna Grant Meeting Room of the Stanley H. Kellerhouse Municipal Building, 1 Van Wyck Street.

For those unable to attend the meeting, it will be livestreamed on the village's website and cable channel 78.

Information on the project thus far can be found on the Village's website.


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Hydrilla is an invasive aquatic perennial that grows rapidly. In some cases, up to an inch per day. Hydrilla stems are long and branching, forming intertwined mats at the water surface. Small spines give leaf margins a toothed appearance. The midrib is often spiny bellow (making it rough to the touch) and reddish when new. Leaves grow along the stem in whorls of 3-6, but often 5 leaflets. Hydrilla plants are usually rooted to the lake bottom, coming up to the surface from up to 12 feet deep. During the late growing season, small white tubers form on the plants' roots that are used for food storage and allow the plant to over-winter. Hydrilla resembles elodea and Egeria, but neither elodea or Egeria produce tubers and are smaller plants. Hydrilla can be found infesting freshwater ponds and lakes, rivers, impoundments, and canals. It tolerates a wide range of light and nutrient levels giving it the advantage over native species. Hydrilla can invade deep, dark waters where most native plants cannot grow. It blocks the sunlight and displaces native plants below with its thick, dense surface mats. Hydrilla decreases dissolved oxygen levels leading to fish kills. Also, decreasing the weight and size of sportfishing can be reduced when natural vegetation is lost. Hydrilla obstructs boating, swimming, and other recreational water activities.

Hydrilla proliferates primarily by stem fragments, although turions (buds) and subterranean tubers also play an important role. The main means of introduction or hydrilla is as castaway fragments on recreational boats and trailers. New colonies can often be found near boat ramps even small fragments can start new populations. The best way to help prevent the spread of hydrilla is by cleaning and drying thoroughly all watercraft, equipment, and trailers after use. Hydrilla remnants can survive for many days. Nutrient availability in the sediment will feed its growth.

Biological Control

Beneficial bacterial products and enzymes such as PZ900 feed on nutrients in the water making them unavailable for plant growth. Reducing nutrients can help prevent invasion.

Physical/Mechanical Control

Because of hydrilla’s rapid growth, mechanical harvesting needs to be performed several times per growing season. Since the mowing and removal cannot capture every single fragment of Hydrilla and water movement can carry away plant material to take root in other areas, monitoring for any new growth to avoid future reinvasion is crucial. Physical removal in conjunction with chemical control will maximize success.

Dyes and colorants reduce aquatic plant growth by limiting sunlight penetration and reducing photosynthesis.

Aeration has also been used as a mechanical approach to hinder pondweed proliferation. Increased water flow can reduce plant density. Additionally, the added oxygen will accelerate the decomposition process of nutrients that pondweeds need to live.

Chemical Control

When used carefully according to the label instruction, aquatic herbicides can be safe and effective management tools. The products that have been successful in treating hydrilla individually or in combination are Reward, Reward with Cutrine-Plus Liquid, Weedtrine D , Aquathol K – liquid , Aquathol Super K – granular , Propeller, Sonar AS and Sonar RTU . A nonionic surfactant Cygnet Plus should be mixed in solution with herbicides when plants are treated.

Rewardis a fast-acting contact herbicide, highly effective in killing any part of the plant that comes into contact with.

Weedtrine D is a contact, non-volatile herbicide for use in controlling submersed and floating aquatics weeds. Weedtrine-D has rapid absorption and herbicide action.

Aquathol K (liquid) is a concentrated, highly soluble contact herbicide, effective against a broad range of aquatic plants.

Aquathol Super K (granular) this contact herbicide has been effective on pondweeds and can be mixed with copper compounds for additional efficiency.

Sonar A.S. is a long-acting systemic herbicide ideal for water bodies with minimal flow. Simply mix Sonar A.S. with water and spray throughout the surface of the water or pour in different spots around the pond. Sonar A.S. does not have water use restrictions.

Sonar RTU is a long-acting, systemic, easy to use herbicide. Sonar RTU does not require mixing, simply open the bottle and treat from the shoreline.

Propeller is a broad spectrum, fast acting contact algaecide/herbicide. It comes in a water dispersible granule that mixes with water to be sprayed or pour. Propeller should be applied to actively growing plants or algal blooms.

CutrinePlus liquid is a chelated copper algaecide that is highly effective on planktonic algae. Available in a liquid concentrate, Cutrine Plus is easy to apply and fast acting.

Cygnet Plusis a nonionic wetting agent, sticker, activator, and penetrant all in one. Cygnet Plus increases the effectiveness of herbicides uptake into the plant tissue.

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From the Blog

Hydrilla & Other Invasive Lake Weeds could be Outlawed.

The Yates County Legislature will not vote on a proposed local law intended to prevent the introduction and movement of aquatic invasive species in Yates County waters during their April 8 meeting as previously planned because additional work needs to be done on the draft law, explains District III Legislator Dan Banach of Milo, who is chairman of the Public Works Committee.

A public hearing on the proposed law will still be held at the beginning of the 1 p.m. meeting Monday.

Although some non-native invasive species have already found their way into the local lakes and waterways, the proposed law was spawned by increased concerns over the spread of hydrilla, an aggressive water weed that has gotten a foothold in the Cayuga Lake Inlet.

The law's intent is to protect the ecology of the navigable water bodies in the county by preventing the introduction of the invasive species.

James Balyszak, who is the Ithaca-based Hydrilla Program Manager through Cornell Cooperative Extension, says at this time the hydrilla infestation is limited to the Cayuga Inlet.

"No hydrilla has been found in Cayuga Lake, or any of the neighboring Finger Lakes (thankfully), and our eradication efforts in the Inlet are helping. In September of 2012, hydrilla was discovered in the Erie Canal in North Tonawanda (near Buffalo).This is not related to the Cayuga Inlet discovery, or the Finger Lakes area exactly, but it is a discovery in another part of New York State," he explains.

According to information provided by the Cornell Cooperative Extension, hydrilla can grow up to a foot a day, and forms a thick dense mat that will block sunlight, kill native plants, and reduces oxygen in the water, altering the fish habitat. Its growth can obstruct boating, swimming and fishing and block intakes at water treatment plants.

Among other things, the proposed law will prohibit the launch of a watercraft into a navigable body of water with any plant or animal or parts visible or attached to any part of the watercraft, including in live wells and bilges, the motor, rudder, anchor or other areas, including the trailer.

Warren, Tompkins and Schuyler County have adopted similar laws while Essex and Washington County are considering laws. In addition, the village of Lake Placid in Essex County and seven towns — Lake Pleasant in Hamilton County Santa Clara, Brighton Harrietstown and Franklin in Franklin County and North Elba and Schroon in Essex County — have all adopted laws. Two other towns in Herkimer and Oneida Counties are considering laws.

If convicted of violating the law, a person faces a fine of $250 or up to 15 days in jail.

When the legislature set the public hearing, District 2 Legislator Richard Willson objected, voting no, saying he thought the effort was a "feel good thing" about the lake, commenting that laws have never been considered to stop the spread of invasive species such as hogweed. Noting that the most frequent transport of seeds is through the wind and via birds, Willson said he doesn't feel a law like this can be enforced and he thinks the effort should be put into developing a plan for when the species do enter the area.

He said he feels effort should be put into education.

Elizabeth Newbold of Cornell Cooperative Extension of Yates County explained that research shows the hydrilla is transported by watercraft.

She also compared the proposed law to similar laws about transporting firewood within New York State, an effort to restrict the movement of non-native insects.

Balyszak says there is a myriad of printed materials from multiple conservation agencies regarding Hydrilla, its infestation and effects, and ways the citizens/boaters can identify, report, and prevent the spread of hydrilla and other invasives.

"During the 2012 season the Finger Lakes Institute managed the Boat Steward Program, which put trained individuals at boat launches on several of the Finger Lakes. These trained individuals helped to educate boaters on clean boating practices, the threat of hydrilla and other invasives, and provided free boat/trailer inspections to boaters (on a voluntary basis after boater consent)," he said, adding, "The Boat Steward Program was quite successful, and will be implemented again this year."

You can find more information, as well as numerical results of the Boat Steward Program at this link: http://flisteward.wordpress.com/

Banach introduced the law, and explained it is an effort to help protect the water inlet for the village of Penn Yan, which supplies water to about 1/3 of Yates County's households.

"Granted, it may be difficult to enforce, but it may keep some out," he said.

Mark Morris, who also represents District III, said the Keuka Lake Association and Seneca Lake Pure Waters Association are behind the efforts to try to reduce the impact of the invasive species.

Giant duckweed

Duckweed is a prevalent aquatic weed in Florida and careful treatment is crucial to Florida ponds and lakes. Giant or big duckweed is still relatively small (1/16 to 1/4 inch) with 1 to 4 light green leaves. Three or more roots (or root-hairs) protrude from each frond. Duckweed tends to grow in dense colonies in quiet water undisturbed by wave action. Often more than one species of duckweed will be grouped together in these colonies.

Water hyacinth has no known direct food value to wildlife and is considered a pest species. For water hyacinth control, Lake Restoration recommends an Open Water Kit, which is also effective in killing cattails and water lilies.

Giant duckweed can be an aggressive invader of Florida ponds and are often found mixed in with other types ofduckweed, mosquito fern, and watermeal. If colonies cover the surface of the water, then oxygen depletion and fish kills can occur. These plants should be controlled before they cover the entire surface of the pond.

For effective Florida duckweed control, we recommend our signature PondRestore Ultra pond weed control kit, which controls and kills a variety of submerged, emergent, and floating pond weeds and treats entire bodies of water.

International investigation discovers bald eagles' killer

A bald eagle's drooped wings show signs of brain infection caused by the bacteria Aetokthonos hydrillicola, which grows on the leaves of the invasive hydrilla plant in human-made lakes. Credit: UGA

The alarm bells began ringing when dozens of eagles were found dead near an Arkansas lake.

Their deaths—and, later, the deaths of other waterfowl, amphibians and fish—were the result of a neurological disease that caused holes to form in the white matter of their brains. Field and laboratory research over nearly three decades has established the primary clues needed to solve this wildlife mystery: Eagle and waterfowl deaths occur in late fall and winter within reservoirs with excess invasive aquatic weeds, and birds can die within five days after arrival.

But until recently, the toxin that caused the disease, vacuolar myelinopathy, was unknown.

Now, after years spent identifying a new toxic blue-green algal (cyanobacteria) species and isolating the toxic compound, an interdisciplinary research group from the University of Georgia and international collaborators have confirmed the structure of this toxin. The results were recently published in the journal Science.

The cyanobacteria grows on the leaves of an invasive water plant, Hydrilla verticillata, under specific conditions: in manmade lakes when bromide is present. The bacteria—and animal deaths from the disease it causes—has been documented in watersheds across the southeastern United States. This is why it's important for anyone in the outdoors—anglers, hunters, birdwatchers and more—to be aware of the signs of this neurological infection and avoid consuming infected animals.

"We want people to recognize it before taking birds or fish from these lakes," said Susan Wilde, an associate professor of aquatic science at the Warnell School of Forestry and Natural Resources who first discovered the cyanobacteria. In some animals, such as birds, turtles, salamanders and even a beaver, the disease manifests as erratic movements or convulsions. Anglers must be even more cautious, though, as it's impossible to detect toxin in fish without obvious symptoms.

"For fish, it's tough. I would avoid eating fish with lesions or some sort of deformities we do see affected fish with slow swimming speeds, but anglers won't be able to see that," added Wilde. "We want people to know the lakes where this disease has been documented and to use caution in consuming birds and fish from these lakes."

Wilde and Warnell graduate students studying the cyanobacteria have compiled maps and a list of affected watersheds.

The most recent study details new mapping of the bacteria's genome, a final piece in the puzzle to understand how it develops and survives. Wilde and others have been studying the cyanobacteria since 2001, when bald eagles began dying in Georgia, South Carolina and North Carolina. The following decades saw the discovery of the cyanobacteria itself, Aetokthonos hydrillicola (Latin for "eagle killer that grows on Hydrilla"), and connections made between the invasive aquatic plant and the animals that eat it.

But until recently, said professor Timo Niedermeyer of the Institute of Pharmacy at Martin Luther University Halle-Wittenberg in Germany, the origin of the brain-decimating disease was a mystery.

Niedermeyer, who has worked with cyanobacteria natural products for years, wanted to help put the pieces together. He contacted Wilde and offered to collaborate. Samples of Hydrilla collected in the field were sent to him, and his lab cultivated the cyanobacteria in the laboratory and sent them back to UGA for further testing. But the tests came back negative: The cyanobacteria from the lab did not induce the disease.

"It's not just the birds that were going crazy, we were too. We wanted to figure this out," said Niedermeyer. Once again, he had colonized leaves sent to him from UGA.

Steffen Breinlinger, a doctoral student in his research group, then used a new imaging mass spectrometer to investigate the composition on the surface of the plant's leaf, molecule by molecule. He discovered a new substance that only occurs on the leaves where the cyanobacteria grows but is not produced in the cyanobacteria cultures. His investigations into the chemical structure of the isolated molecule revealed five bromine atoms.

"The structure is really spectacular," said Breinlinger. The properties are unusual for a molecule formed by cyanobacteria, and they provide an explanation for why the toxin did not form under laboratory conditions, where bromide isn't present. "We then added bromide to our lab cultures, and the cyanobacteria started producing the toxin."

After almost a decade of testing the isolated molecule and collaboration between the labs in Germany and Georgia, they had their proof: the molecule does trigger vacuolar myelinopathy. The researchers call their discovery aetokthonotoxin, "poison that kills the eagle."

"Finally, we did not only catch the murderer, but we also identified the weapon the cyanobacteria used to kill those eagles," said Wilde.

The neurological disease has not yet occurred in Europe, and no instance of the toxin-forming cyanobacterium has been reported. Humans are not yet known to be affected by vacuolar myelinopathy, although the study did successfully affect chickens with the toxin, and Wilde continues to test fish and waterfowl such as ducks and coots for the disease.

Watch the video: Video demo - Photosynthesis with bubbling pondweed