Professor Talks About Ways To Combat Lake Weeds
By PATRICK L. FANELLI
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11/16/2006 - Insects may be the most effective way to control Eurasian watermilfoil, Chautauqua Lake’s ‘‘problem plant,’’ according to aquatic ecology expert Bob Johnson of Cornell University.
After years studying Chautauqua Lake and other water bodies across the state, Johnson thinks moths and beetles that feed on the aggravating weed might prove more successful in the long run than treating the lake with herbicides.
‘‘It isn’t a long-term deal,’’ Johnson said of herbicides during a presentation Wednesday evening in the Southwestern Central High School auditorium.
‘‘These are all short-term fixes.’’
See MOTH On Page A-3
For years, Johnson has been studying a type of pyralid moth called Acentria Ephemerella that feeds on milfoil — the plant that sprung up dramatically over the summer in Burtis Bay and other areas in the lake.
‘‘There are lots of documented declines associated with the moth,’’ Johnson said, discussing his experiences with Cayuga Lake on which Cornell University is located.
‘‘We had a dramatic decline of Eurasian watermilfoil to the level where after three years there was almost none in the north end.’’
Another insect that feeds on milfoil are weevils, a type of beetle, called Euhrychiopsis Lecontei — but Johnson believes the moth is a more effective herbivore.
‘‘One of our tasks was to monitor Eurasian watermilfoil out there and also if the insects out there are attacking it,’’ said Johnson, who has been working with the Chautauqua Lake Association to better understand the invasive weeds and their relationship with insect populations. ‘‘In the northern basin, we have more luck. We’re trying to figure out why some places have higher numbers of insects.’’
More Moths
Johnson’s work has not only involved monitoring the insect populations, but adding to them as well.
‘‘The other issue is, can we use this as a biocontrol?’’ Johnson said. ‘‘So, for the moth — which we think is a better herbivore — we have been augmenting (the population).’’
Thousands of moth larvae were added to Burtis Bay — notorious for its heavy concentration of weeds — during the winter of 2002, and there was very little milfoil the following summer. Johnson said he can’t take credit for that, though, describing some sort of unknown event that took place underneath the surface that killed off much of the plant.
But the Chautauqua Lake Partnership can’t take much credit either, Johnson said. The CLP applied herbicides to Burtis Bay the previous summer, since herbicides are only applied up to a certain distance from shore, he explained.
‘‘We didn’t see any effect of the herbicides beyond where they made the application,’’ he said.
The weeds — noticable by the red tips that extend above the surface — began appearing well before the summer season even began. The intense growth may have been fueled by plenty of sunlight the plants received due to inadequate ice cover during the mild winter, but the absence of the weevil population may have also had an effect.
‘‘They didn’t get out there soon enough to stop this,’’ Johnson said, gesturing toward a picture of Burtis Bay on the projection screen.
Johnson said he and his crew will be adding more moths to Burtis Bay next season, though he thinks it’s unlikely the problem will be nearly as bad as it was this year.
‘‘Chances are that Burtis Bay isn’t going to look like it did this year,’’ Johnson said. ‘‘That just doesn’t happen in so many years.’’
A Healthy Lake
Eurasian watermilfoil may be a nuisance, Johnson said — but other types of plants are essential for the health of Chautauqua Lake.
‘‘We do need aquatic plants growing on the bottom of the lake,’’ he said.
For one thing, native plants that typically do not extend as far up from the surface compete with the milfoil, making it more difficult for milfoil to thrive. For instance, in recent years herbicides were applied to Waneta Lake in Steuben County to kill off all the plants growing beneath the surface. Within a few years, with no other plants to compete with, the milfoil returned ‘‘with a vengeance,’’ according to Johnson.
However, some herbicides only target milfoil — such as Aquathol K, which was used by the Chautauqua Lake Partnership in 2002.
Another reason aquatic plants are essential is they keep sediment on the bottom, Johnson said. Without plants, wind will kick up the sediment and the nutrients it carries with it will fuel algae growth.
But other elements fuel algae growth, especially water runoff from development, lawns and farmland.
‘‘Some things we need to really work on,’’ Johnson said. ‘‘We need to continue to promote good watershed practices. We have to somehow limit the amount of nitrogen and phosphorous anyway possible.’’
For Johnson — who heads the Research Ponds Facility of Cornell University’s Ecology and Evolutionary Biology department — Chautauqua Lake is one of his main projects. He works on the lake gathering data with a team of research assistants for much of the year, and he will present the annual report on his findings from 2006 early next year.
Wednesday’s presentation was sponsored by the Chautauqua Lake Association.
After years studying Chautauqua Lake and other water bodies across the state, Johnson thinks moths and beetles that feed on the aggravating weed might prove more successful in the long run than treating the lake with herbicides.
‘‘It isn’t a long-term deal,’’ Johnson said of herbicides during a presentation Wednesday evening in the Southwestern Central High School auditorium.
‘‘These are all short-term fixes.’’
See MOTH On Page A-3
For years, Johnson has been studying a type of pyralid moth called Acentria Ephemerella that feeds on milfoil — the plant that sprung up dramatically over the summer in Burtis Bay and other areas in the lake.
‘‘There are lots of documented declines associated with the moth,’’ Johnson said, discussing his experiences with Cayuga Lake on which Cornell University is located.
‘‘We had a dramatic decline of Eurasian watermilfoil to the level where after three years there was almost none in the north end.’’
Another insect that feeds on milfoil are weevils, a type of beetle, called Euhrychiopsis Lecontei — but Johnson believes the moth is a more effective herbivore.
‘‘One of our tasks was to monitor Eurasian watermilfoil out there and also if the insects out there are attacking it,’’ said Johnson, who has been working with the Chautauqua Lake Association to better understand the invasive weeds and their relationship with insect populations. ‘‘In the northern basin, we have more luck. We’re trying to figure out why some places have higher numbers of insects.’’
More Moths
Johnson’s work has not only involved monitoring the insect populations, but adding to them as well.
‘‘The other issue is, can we use this as a biocontrol?’’ Johnson said. ‘‘So, for the moth — which we think is a better herbivore — we have been augmenting (the population).’’
Thousands of moth larvae were added to Burtis Bay — notorious for its heavy concentration of weeds — during the winter of 2002, and there was very little milfoil the following summer. Johnson said he can’t take credit for that, though, describing some sort of unknown event that took place underneath the surface that killed off much of the plant.
But the Chautauqua Lake Partnership can’t take much credit either, Johnson said. The CLP applied herbicides to Burtis Bay the previous summer, since herbicides are only applied up to a certain distance from shore, he explained.
‘‘We didn’t see any effect of the herbicides beyond where they made the application,’’ he said.
The weeds — noticable by the red tips that extend above the surface — began appearing well before the summer season even began. The intense growth may have been fueled by plenty of sunlight the plants received due to inadequate ice cover during the mild winter, but the absence of the weevil population may have also had an effect.
‘‘They didn’t get out there soon enough to stop this,’’ Johnson said, gesturing toward a picture of Burtis Bay on the projection screen.
Johnson said he and his crew will be adding more moths to Burtis Bay next season, though he thinks it’s unlikely the problem will be nearly as bad as it was this year.
‘‘Chances are that Burtis Bay isn’t going to look like it did this year,’’ Johnson said. ‘‘That just doesn’t happen in so many years.’’
A Healthy Lake
Eurasian watermilfoil may be a nuisance, Johnson said — but other types of plants are essential for the health of Chautauqua Lake.
‘‘We do need aquatic plants growing on the bottom of the lake,’’ he said.
For one thing, native plants that typically do not extend as far up from the surface compete with the milfoil, making it more difficult for milfoil to thrive. For instance, in recent years herbicides were applied to Waneta Lake in Steuben County to kill off all the plants growing beneath the surface. Within a few years, with no other plants to compete with, the milfoil returned ‘‘with a vengeance,’’ according to Johnson.
However, some herbicides only target milfoil — such as Aquathol K, which was used by the Chautauqua Lake Partnership in 2002.
Another reason aquatic plants are essential is they keep sediment on the bottom, Johnson said. Without plants, wind will kick up the sediment and the nutrients it carries with it will fuel algae growth.
But other elements fuel algae growth, especially water runoff from development, lawns and farmland.
‘‘Some things we need to really work on,’’ Johnson said. ‘‘We need to continue to promote good watershed practices. We have to somehow limit the amount of nitrogen and phosphorous anyway possible.’’
For Johnson — who heads the Research Ponds Facility of Cornell University’s Ecology and Evolutionary Biology department — Chautauqua Lake is one of his main projects. He works on the lake gathering data with a team of research assistants for much of the year, and he will present the annual report on his findings from 2006 early next year.
Wednesday’s presentation was sponsored by the Chautauqua Lake Association.
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