HYBRID WATERMILFOIL: Challenges and Possible Control Strategies
Keegan Lund
MnDNR Invasive Species Program
MnDNR ‐
Invasive Species Program
Aquatic Invaders Summit II
October 6th, 2016
OUTLINE
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What is Hybrid watermilfoil?
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How is it different from Eurasian watermilfoil?
How can I identify Hybrid watermilfoil?
How can I identify Hybrid watermilfoil?
Management considerations & takeaways
Hybrid watermilfoil – What is it?
Northern watermilfoil Northern watermilfoil
Eurasian watermilfoil Eurasian watermilfoil
Genetic cross of Northern watermilfoil (native) with Eurasian watermilfoil (invasive) Photos by MNDNR
Hybrid watermilfoil – How is it different?
Resulting cross may behave differently and exhibit:
Photos by MNDNR
Hybrid watermilfoil – How is it different?
Resulting cross may behave differently and exhibit:
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A competitive advantage over both parents
Photos by MNDNR
Hybrid watermilfoil – How is it different?
Resulting cross may behave differently and exhibit:
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A competitive advantage over both parents
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More aggressive growth
gg
g
Photos by MNDNR
Hybrid watermilfoil – How is it different?
Resulting cross may behave differently and exhibit:
•
A competitive advantage over both parents
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More aggressive growth
gg
g
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Decreased sensitivity to herbicides and less effective control under certain management g
scenarios
Photos by MNDNR
Hybrid watermilfoil – How is it different?
Resulting cross may behave differently and exhibit:
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A competitive advantage over both parents
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More aggressive growth
gg
g
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Decreased sensitivity to herbicides and less effective control under certain management g
scenarios
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General invasive characteristics
Photos by MNDNR
Hybrid watermilfoil – What does it mean?
We know this:
• Hybrids in some
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past studies have p
shown reduced sensitivity to 2,4‐D and fluridone compared with pure EWM ((Berger et al 2015)
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)
(La Rue et al 2013)
(Glomski et al 2010)
Hybrid watermilfoil is invasive & mayy require different management q
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strategies than pure EWM
Photos by MNDNR
Hybrid watermilfoil –
How to identify?
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First know the parents…
Photos by MNDNR
Northern Watermilfoil
Eurasian Watermilfoil
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Native range includes Minnesota
Invasive in Minnesota
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Leaflet 5‐11 per side
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Leaflets 12‐20 per side
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Stems thick and whitish or green
Stems thick and whitish or green
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Stems thin and pink/red
Stems thin and pink/red
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Leaflet holds shape out of water and •
Leaflet is limp out of water and is stout in appearance
is stout in appearance
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Leaflet shape round with pointed tip
delicate in appearance
delicate in appearance
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Leaflet shape oval with blunt tip
Photos by MNDNR
Hybrid watermilfoil –
How to identify?
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Often looks “funny” & shows in between physical characteristics:
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Intermediate leaflet count – (11‐13 is common)
(11 13 i
)
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Slightly thicker plant stems than EWM
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L fl t i
Leaflet is more stout than pure EWM
t t th
EWM
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Leaflet shape may be in between
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Multiple genotypes
Photos by MNDNR
Genetic Verification
Definitive ID can be done through genetic screening:
• GenPass LLC is one option
https://www.facebook.com/GenPassID/
• Partner with universities??? – Some universities or government units may be doing invasives plant research (i.e. Dan Larkin ‐ MAISRC, Ryan Thum ‐ MSU Missoula)
Photos by MNDNR
To screen or not to screen?
Influencing Factors:
1. What is your reasoning?
‐ Past treatment failures
2. COST $$$ ‐ How many samples are sufficient?
3. Implications of results… ‐ How does knowing affect future management plans?
management plans?
Photos by MNDNR
To screen or not to screen?
If it is not broke, don’t fix it…
If current management practices are providing the desired outcomes, maybe don’t change them
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Photos by MNDNR
Failed milfoil treatments – ask yourself???
Before conducting genetic screening consider:
1. Was your treatment plan sound (adequate CET)?
2. Is the area you are trying to control reasonable? •
Spot treatment (narrow band with a steep drop) (
b d
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Insufficient treatment size (too small)
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Treatment timing (spring vs. summer vs. fall) 3. Do you have Northern watermilfoil present in your lake?
HYBRID MANAGEMENT CONSIDERATIONS
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Genetic verification
Alternative herbicides or herbicide use
Alternative herbicides or herbicide use patterns if your past results are not acceptable
Herbicide susceptibility screening (?)
Monitor, monitor, monitor Three Hybrid Milfoil Treatments in MN
LAKE
DATE
TREATED WITH
OUTCOME
Crooked
2015
2,4‐D
2,4
D
Significant regrowth, poor control
Significant regrowth, poor control
Crooked
2016
Sonar One
(
(granular fluridone)
l fl id
)
Very good control, limited effects on natives
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Ham
2015
2,4‐D
Significant regrowth, poor control
Ham
2016
Renovate OTF
(granular Triclopyr)
Very good control, some damage to natives but have recovered
Josephine
2015
2,4‐D
Very good control, limited effects on natives
Crooked Lake Hybrid Milfoil Treatment
MAY 2015 ‐ Delineation
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JUNE 2015 ‐ 2,4‐D Treatment
25.3 acres treated with 2,4‐D
JULY 2015 ‐ Post Treatment
Crooked Lake Hybrid Milfoil Treatment
MAY 2016 ‐ Delineation
MAY 2016 ‐ Sonar One AUGUST 2016
24.9 acres treated with Sonar One (granular fluridone)
SEPT 2016
Ham Lake Hybrid Milfoil Treatment
MAY 2015 ‐ Delineation
MAY 2015 JUNE 2015 ‐ Triclopyr Treatment
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SEPT 2015 ‐ Post Treatment
19.4 acres treated with Renovate OTF
Ham Lake Hybrid Milfoil Treatment
MAY 2016 – CLP Delineation
MAY 2016 CLP Delineation
Lake Josephine Hybrid Milfoil Treatment
MAY 2015 ‐ Delineation
JUNE 2015 ‐ 2,4‐D Treatment
25.1 acres treated with 2,4‐D
May 2016 ‐ Delineation
Takeaways
• Genetic verification may provide information
• Pre and post‐treatment monitoring
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– Lake consultants or commercial applicators
– Partners (MAISRC Tracker, citizen science, LGUs, etc.)
Partners (MAISRC Tracker citizen science LGUs etc )
• CET relationships • Consider herbicide susceptibility screening
C id h bi id
tibilit
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– Currently costly and limited options
– (CSU, Grand Valley State, U Florida, SePRO Labs, ???)
Takeaways
• Treatment area size:
– Effective treatment size – is an area to small?
• Herbicide alternatives to 2,4‐D:
– Formulations of Triclopyr
Formulations of Triclopyr
– Formulations of Fluridone
– Combinations (Endothall with 2,4‐D)
Combinations (Endothall with 2 4‐D)
– Diquat or other contacts for small areas
– Others???
• Talk to your applicators and ask questions
References
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Berger, S.T., M. D. Netherland, and G. MacDonald. 2015. Laboratory documentation of multiple‐
herbicide tolerance to fluridone, Norflurazon, and Topramazone in a hybrid watermilfoil population. Weed Science 63:235‐241
Glomski, L. M., and M.D. Netherland. 2010. Response of Eurasian watermilfoil and hybrid watermilfoil to low use rates and extended exposures of 2,4‐D and triclopyr. Journal of Aquatic Plant Management 48:12‐14.
LaRue EA MP Zuellig MD Netherland MA Heilman and RA Thum 2013 Hybrid watermilfoil lineages
LaRue, EA, MP Zuellig, MD Netherland, MA Heilman, and RA Thum. 2013. Hybrid watermilfoil lineages are more invasive and less sensitive to a commonly used herbicide than their exotic parent (Eurasian watermilfoil). Evolutionary Applications 6: 462‐471.
Parks, Syndell, and Ryan A. Thum. 2014. Benefits of incorporating genetic identification of watermilfoils into aquatic vegetation mapping. Presentation included in the Pre‐Final agenda for ilf il i
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i i l d d i h P Fi l
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which an abstract was printed in 54th Annual Meeting of the Aquatic Plant Management Society to be held at the Hilton Savannah DeSoto in Savannah, GA, July 13‐16, 2014. Poovey, A.G., J.G. Slade, and M.D. Netherland. 2007. Susceptibility of Eurasian watermilfoil: (Myriophyllum spicatum) and a milfoil hybrid (M. spicatum x M. sibiricum) to triclopyr and 2,4‐D amine. Journal of Aquatic Plant Management 45:111‐115.
Zuellig M.P. and R.A. Thum 2012. Multiple introductions of invasive Eurasian watermilfoil and recurrent hybridization with northern watermilfoil in North America. Journal of Aquatic Plant y
q
Management 50:1‐19.
Thank you!
[email protected]
651‐259‐5828