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Eurasian watermilfoil
(Myriophyllum spicatum)

Eurasian watermilfoil

 

 

 

eurasian vs native watermilfoil
Eurasian vs Native watermilfoil

 

 

eurasian watermilfoil map
Click here to open printable map

 

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Characteristics: (APIS-U.S. Army Corps) Eurasian watermilfoil is an invasive, submersed (underwater) aquatic plant accidentally introduced in the 1940s to North America from Europe, where it is widespread. Eurasian watermilfoil is a stringy, submerged plant that quickly proliferates in North American water bodies. It is highly invasive and agressively competes with native plant communities reducing biodiversity. Dense mats clog propellers, impair swimming, restrict boating and fishing accesses, and affect water quality. 

Eurasian watermilfoil is recognized primarily by its whorls of four feather-like leaves around the stems. Each leaf is finely divided into paired leaflets, typically 12 to 21 pairs per leaf. The number of stems per plant increases as the plant ages. Each individual stem branches several times as it nears the water surface, creating a dense floating mat over the surface of the lake. Dense Eurasian watermilfoil beds usually occur in water between 3 and 20 feet deep. The tops of the milfoil plants, both stems and leaves, often turn red in color.

(Matt Rehwald, WDNR Bureau of Watershed Management): There are 7 native water-milfoils found in Wisconsin.  There is also the northern water-milfoil x EWM hybrid.  If you suspect the EWM hybrid, take the plants to your WDNR APMP specialist.  If they suspect the hybrid, they should contact Michael Moody to see about analysis.  Samples must go through DNR APMP staff and not through consultants and lake groups.

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Methods of control: While eradication is rare, control is possible. Options for effective control vary with size and duration of the infestation, water quality conditions, lake bottom conditions, water flow, willingness to use permitted herbicides and financial resources. All mechanical and chemical control measures require permitting by the WDNR and development of an aquatic plant management plan.

Hand pulling can be effective when the colony size is small, water clarity is good and the lake bottom is soft enough to enable divers to completely remove plant roots. Care must be taken to avoid releasing plant fragments into the water column. Volunteer divers on Forest Lake in the town of Land O' Lakes have been successfully managing EWM by hand pulling following a one time only initial chemical application.

Mechanical harvesting is generally not permitted. Extreme infestations might qualify for harvesting if no other control methods are feasible. Mechanical harvesting requires a WDNR permit which will likely require an aquatic plant management plan.

Chemical control with WDNR permitted aquatic herbicides applied by licensed applicators is expensive and often controversial in terms of effectiveness and environmental safety. Repeated applications, often long term, are necessary for effective control. As with other control methods requiring WDNR permitting, chemical control programs require an aquatic plant management plan.

Biological control is an option, but not always a good one. The most effective method is the Milfoil Weevil which is native to North America and normally feeds on native Milfoil. However, if given the choice, it prefers to feed on Eurasian Water Milfoil. These sesame seed size weevils lay their eggs in the stems of the milfoil and when the larvae hatch, they eat the milfoil and kill the plant. The weevils require certain shoreline conditions for over wintering. They are also a food source for certain fish species such as sunfish. Therefore, maintaining a population of the weevils suitable for EWM control can be difficult and extremely expensive. No WDNR permit is required prior to introducing the Milfoil Weevil.

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Methods of early detection: Watch for early spring plant growth. Near to surface growth and even surface matting will be detectable in advance of native aquatic plant growth. Monitoring the lake surface for floating fragments and shorelines for washed up plant fragments can provide evidence of colonies not yet visible from the water surface. Rake drags in low density colonies is not as effective for detecting Eurasian watermilfoil as it is for Curly-leaf pondweed as EWM is much more fragile and often breaks into pieces too small to adhere to a rake. SCUBA or snorkel diving when water conditions are suitable are good techniques for early detection.

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2008 Chemical control statistics
2008 was a benchmark year for EWM management in Vilas County. For the first time ever, 17 area water bodies were subjected to chemical control programs, all with WDNR approved plant management plans and with State funding covering as much as 75% of the costs for pre and post treatment assessment of the aquatic plant communities, pre-treatment mapping, permitting fees and the actual placement of the chemicals by a licensed applicator.

Conditions at the time of chemical application were ideal; water temperatures on all treated lakes was at or below 62 degrees farenheit and winds were light to calm. The chemical applicator used high tech electronic distribution equipment enabling precise control of both placement and concentration of the chemicals.

The following table summarizes the 2008 spring chemical control activity. Clicking on the lake names opens maps showing the precise treatment locations:

2008 Chemical treatment summary

LAKE NAME
(Click name to see trtmnt site map) 		ACRES 2,4-D NAVIGATE GRANULES @ 100 LBS/ACRE

ACRES 2,4-D NAVIGATE
GRANULES @ 150 LBS/ACRE

TTL LBS GRANULAR 2,4-D USED ACRES 2,4-D WEEDBAR
LIQUID 		TTL GALS 2,4-D LIQUID USED TREATMENT DATE(S) WATER TEMP. (F) AIR TEMP. (F) WIND SPEED (MPH) WIND DIR.
E.R. CHAIN

CATFISH
LAKE

 5.4 30.1 5,055 0 0 05/31/08 57.9 57.9 5 - 10 S
          06/01/08 59.0 64.9 CALM NA
                     
CRANBERRY LAKE
22.2 6.7 3,225 0 0 05/30/08 60.8 62.6 5 SW
                   
DUCK
LAKE
6.6 0.0 660 0 0 05/30/08 57.9 54.0 5 SW
                   
EAGLE
LAKE

0.0

 14.7 2,205 0 0 06/01/08 59.0 70.0 0 - 5 S
                   
EAGLE
RIVER
0.0 17.8 2,670 0 0 05/29/08 62.1 70.0 CALM NA
                   
LYNX
LAKE
 0.5 7.6 1,265 0 0 06/02/08 59.9 70.0 CALM NA
                   
OTTER
LAKE
 5.0 4.9 1,235 0 0 06/01/08 61.0 72.0 0 - 5 SW
          06/02/08 57.9 60.1 CALM NA
                   
SCATTERING RICE LAKE
29.5 19.8 5,920 0 0 05/28/08 57.9 57.9 0 - 5 W
                   
VOYAGEUR
LAKE
 0.0 3.4 510 0 0 06/01/08 59.0 70.1 CALM NA
                   
WATERSMEET
LAKE
 0.0 8.5 1,275 0 0 05/29/08 57.9 57.9 0 - 5 W
                   
YELLOW BIRCH LAKE
6.9 5.6 1,530 0 0 06/02/08 60.1 70.0 0 - 5 SW
 
NON CHAIN
                   
BIG SAND LAKE
0.0 21.0 3,159 106.6 1,025 06/03/08 55.4 60.8 5 - 15 E
06/04/08 57.2 60.8 0 - 5 E
06/05/08 59.0 60.8 0 - 5 E
LITTLE ST. GERMAIN
11.5 12.6 3,040 0 0 06/07/08 60.8 60.8 5 SE
LONG
LAKE
0.0 32.2 4,830 0 0 06/07/08 50.0 60.1 0 - 5 W
TWIN (N) LAKE
0.0 15.0 2,250 0 0 05/20/08 51.1 60.1 5 - 15 NW
05/21/08 51.1 55.0 0 - 10 NW
TWIN (S)
LAKE
0.0 49.9 7,485 0 0 05/20/08 51.1 60.1 5 - 15 NW
05/21/08 51.1 55.0 0 - 10 NW
GRESHAM (UPPER)
0.0 8.1 1,215 0 0 05/12/-8 50.0 45.0 0 - 5 SE
  ALL LAKES E.R. CHAIN
TTL ACRES TREATED 452.1 195.2
*TTL LBS
NAVIGATE 2,4-D 		*47,520 *25,550
*TTL GALS
WEEDBAR 2,4-D		 *1,025 0
TTL LBS 2,4-D 16,583 6,822                

*NOTE: 
Navigate brand granular 2,4-D is 73.3% by weight inactive ingredient and 26.7% 2,4-D.  Of the 47,520 pounds applied, active ingredient accounted for 12,688 pounds.
Weedbar 64 brand liquid 2,4-D contains 3.8 pounds of active ingrediant per gallon. Of the 1,025 gallons applied, active ingrediant accounted for 3,895 pounds.

 

2009 Chemical treatment summary

LAKE NAME
(Click name to see trtmnt site map) 		ACRES 2,4-D NAVIGATE GRANULES @ 100 LBS/ACRE ACRES 2,4-D NAVIGATE GRANULES @ 150 LBS/ACRE ACRES 2,4-D NAVIGATE GRANULES @ 175 LBS/ACRE TTL LBS GRANULAR 2,4-D USED ACRES 2,4-D
DMA4IVM
LIQUID 		TTL GALS 2,4-D LIQUID USED TREATMENT DATE(S) WATER TEMP. (F) AIR TEMP. (F) WIND SPEED (MPH) WIND DIR.
E.R. CHAIN
 

CATFISH
LAKE

 0.0 26.0 0.0 3,900 0.0 0 05/18/09 51.8 59.0 15 SW
                       
CRANBERRY LAKE
3.4 31.0 1.7 5,288 0.0 0 05/19/09 53.6 59.0 5 SW
                     
DUCK
LAKE
0.0 10.7 0.0 1,605 0.0 0 05/20/09 55.4 57.2 8 SW
                     
EAGLE
LAKE
 0.0 3.3 5.9 1,528 0.0 0 05/21/09 55.4 57.2 O -
                     
EAGLE
RIVER
0.0 54.8 0.0 8,220 0.0 0 05/22/09 59.0 69.8 5 SW
              05/26/09 59.0 55.4 5 SE
                     
LYNX
LAKE
 0.0 3.1 0.0 465 0.0 0 05/20/09 57.2 64.4 12 SW
                     
OTTER
LAKE
 0.0 6.6 0.0 990 0.0 0 05/20/09 57.2 80.6 25 SW
                     
SCATTERING RICE LAKE
0.0 44.0 4.8 7,440 0.0 0 05/21/09 60.8 60.8 5 NW
                     
VOYAGEUR
LAKE
 0.0 0.4 0.0 60 0.0 0 05/21/09 55.4 57.2 55.4 57.2
                     
WATERSMEET
LAKE
 0.0 76.7 0.0 11,505 0.0 0.0 05/26/09 59.0 55.4 5 SE
              05/27/09 57.2 50.0 5 NE
                     
YELLOW BIRCH LAKE
1.2 10.0 0.0 1,620 0.0 0 05/22/09 57.2 55.4 5 SW
                       
NON CHAIN
                     
0.0 3.1 0.0 435 0.0 0 05/15/09 55.4 59.0 E NE
                     
0.0 0.0 0.0 0 70.6 480 05/28/09 55.4 69.8 5 S
                     
0.0 1.8 0.0 270 0.0 0 08/10/09 71.6 80.6 5 SW
                       
0.0 40.2 0.0 6,030 0.0 0 05/15/09 53.6 44.6 5 NE
                     
LONG
LAKE
0.0 45.5 0.0 6,825 0.0 0 05/12 51 60 5-15 SW
              05/13 51 60 7-17 SW
  0.0 0.0 0.0 0 71.8 741.3 05/14 52 55 5-15 SW
              05/15 52 43 5-8 SW
                       
SILVER
LAKE
0.0 3.4 0.0 510 0.0 0 05/15/09 57.2 59.0 10 S
                     
TWIN (N) LAKE
0.0 6.2 0.0 930 0.0 0 05/30/09 59.0 59.0 15 W
                     
TWIN (S)
LAKE
0.0 0.0 0.0 0 167.4 1,045 05/30/09 59.0 59.0 15 W
                     
GRESHAM (UPPER)
0.0 3.1 6.8 1,825 0.0 0 05/10/09 51.8 55.4 5 W
 
  ALL LAKES E.R. CHAIN  
TTL ACRES TREATED 703.5 272.4  
*TTL LBS
NAVIGATE 2,4-D		 *59,446 *42,621  
*TTL GALS LIQUID
DMA 4 IVM 2,4-D		 *2,266.3 0  
TTL LBS 2,4-D 24,483 11,380                  

*NOTE: 
Navigate brand granular 2,4-D is 73.3% by weight inactive ingredient and 26.7% 2,4-D.  Of the 59,446 pounds applied, active ingredient accounted for 15,872 pounds.
Dow DMA 4 IVM brand liquid 2,4-D contains 3.8 pounds of active ingrediant per gallon. Of the 2,266 gallons applied, active ingrediant accounted for 8,611 pounds.

 

2010 Chemical treatment summary

LAKE NAME
ACRES 2,4-D NAVIGATE GRANULES @ 100 LBS/ACRE ACRES 2,4-D NAVIGATE GRANULES @ 150 LBS/ACRE ACRES 2,4-D NAVIGATE GRANULES @ 175 LBS/ACRE ACRES 2,4-D NAVIGATE GRANULES @ 200 LBS/ACRE ACRES 2,4-D RENOVATE MAX G #67690-50 TTL LBS GRANULAR 2,4-D USED ACRES 2,4-D
DMA4IVM
LIQUID 		ACRES 2,4-D WEEDESTROY #228-145 TTL GALS 2,4-D LIQUID USED TREATMENT DATE(S) WATER TEMP. (F) AIR TEMP. (F) WIND SPEED (MPH) WIND DIR.
E.R. CHAIN
                           

CATFISH
LAKE

 0 38.9 5.0 27.5 0 12,210 0 0 0 5/18 & 5/19 57.9 62.6 0 NA
                             
CRANBERRY LAKE
0 38.4 2.6 0 0 6,215 0 0 0 5/21 59.9 69.9 5 E
                           
DUCK
LAKE
0 8.7 1,305 0 0 1,305 0 0 0 5/23 64.0 59.9 10 SE
                           
EAGLE
LAKE
 0 13.4 0 2.4 0 2,490 0 0 0 5/22 63.9 59.9 3 SE
                           
LYNX
LAKE
 0 3.7 0 0 0 555 0 0 0 5/23 64.0 59.9 10 SE
                           
OTTER
LAKE
 0 3.2 0 1.2 0 720 0 0 0 5/23 64.0 59.9 10 SE
                           
SCATTERING RICE LAKE
0 0 0 0 0 0 67 0 440 5/20 59.9 55.0 3 W
                           
VOYAGEUR
LAKE
 0 2.8 0 0 0 420 0 0 0 5/22 63.8 59.9 0 NA
                           
WATERSMEET
LAKE
 0 44.4 5.2 0 0 7,570 0 0 0 5/24 & 5/25 69.5 79.8 3 S
                           
YELLOW BIRCH LAKE
0 6.5 14.4 0 0 3,495 0 0 0 5.23 63.9 75.0 10 w
                             
NON CHAIN
                           
ARROWHEAD
LAKE
0 1.7 0 1.1 0 475 0 0 0 6/1 69.9 78.9 10 sw
                           
BIG SAND LAKE
0 0 0 0 0 0 0 229.2 2,640 5/20 62 75 0 NA
                           
LITTLE ST. GERMAIN
0 21.5 0 11.4 0 5,505 0 0 0 5/22 55.0 69.9 0 NE
                           
LONG
LAKE
0 0 0 0 0 0 142.1 0 1,179 5/24 & 5/25 48.5 85 3-10 W
                             
TWIN (N) LAKE
0 0 0 0 26.8 8,440 0 0 0 5/26 67 70 10 N
                           
TWIN (S)
LAK0E
0 0 0 0 0 0 0 161.2 2,160 5/25 & 5/26 67 80 5-10 N-NW
                           
GRESHAM (UPPER)
0 5.6 0 9.7 0 2,780 0 0 0 5/9 51.8 32 2 NE
                           
  ALL LAKES E.R. CHAIN

E.R. CHAIN
% TOTAL

                     
TTL ACRES TREATED 2,200.3 1,590.3 72.3%                      
*TTL LBS granular
2,4-D (All formulations)
52,180
34,980
67.0%
                      
*TTL GALS liquid
2,4-D (All formulations)		 6,419 440 6.8%                      

 

2011 Chemical treatment summary

LAKE NAME
ACRES 2,4-D NAVIGATE GRANULES
@ 100 LBS/ACRE 		ACRES 2,4-D NAVIGATE GRANULES
@ 150 LBS/ACRE 		ACRES 2,4-D NAVIGATE GRANULES
@ 175 LBS/ACRE 		ACRES 2,4-D NAVIGATE GRANULES
@ 200 LBS/ACRE		 ACRES 2,4-D RENOVATE MAX G #67690-50 ACRES 2,4-D
SCULPIN G
#67690-49		 TTL LBS GRANULAR HERBICIDE USED ACRES 2,4-D
DMA4IVM
LIQUID 		ACRES 2,4-D WEEDESTROY #228-145

TTL GALS
LIQUID
HERBICIDE
USED

TREATMENT DATE(S)
E.R. CHAIN
                     

CATFISH
LAKE

 0 0 0 11.8 0 0 2,360 0 0 0 05/31
                       
CRANBERRY LAKE
0 5.9 8.4 4.0 0 0 3,155 0 0 0 05/27
                     
DUCK
LAKE
0 0 0 0 0 0 0 0 0 0 N/A
                     
EAGLE
LAKE
 0 0 0 9.4 0 0 1,880 0 0 0 06/02
                     
LYNX
LAKE
 0 0 0 0 0 0 0 0 0 0 N/A
                     
OTTER
LAKE
 0 0 0 9.7 0 0 1,940 0 0 0 06/02
                     
SCATTERING RICE LAKE
0 3.4 0 1.3 0 0 770 0 0 0 05/31
                     
VOYAGEUR
LAKE
 0 0 0 0.6 0 0 120 0 0 0 05/31
                     
WATERSMEET
LAKE
 0 9.2 20.0 3.5 0 0 5,580 0 0 0 05/26
                     
YELLOW BIRCH LAKE
0 0 4.4 1.4 0 0 150 0 0 0 05/27
                       
NON CHAIN
                     
ARROWHEAD
LAKE
0 0 0.5 1.1 0 0 308 0 0 0 06/03
                     
BIG SAND LAKE
0 0 0 0 0 0 0 0 12.6 78 06/03
                     
LITTLE ST. GERMAIN
0 0 0 0 0 29.6 6,292 0 0 0 05/26
                     
LONG
LAKE
0 0 0 0 0 0 0 0 91.8 914 06/06 - 06/08
                       
TWIN (N) LAKE
0 0 0 0 15.4 0 6,944 0 0 0 06/26
                     
TWIN (S)
LAKE
0 0 0 0 0 0 0 0 0 0 N/A
                     
GRESHAM (UPPER)
0 0 0 0 0 6.6 1,925 0 0 0 05/16
                     
  ALL LAKES E.R. CHAIN

E.R. CHAIN
% TOTAL

               
TTL ACRES TREATED 250.6 93 37.1%                
*TTL LBS granular
2,4-D (All formulations)		 31,274 15,805 50.5%                
*TTL GALS liquid
2,4-D (All formulations)		 992 0 0%                

 

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Links to pdf documents
Native water-milfoil turion fact sheet
Eurasian vs Native water-milfoil
Chemical control - U. S. Army Corps report

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Links to other sites
Wisconsin DNR
Minnesota DNR
Minnesota Sea Grant
Western Aquatic Plant Management Society
Canadian Wildlife Service
The milfoil weevil
Aquatic Plant Management in Wisconsin - WDNR guidelines (Caution - very large download)

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