Ecological Weed Management EPM13 - PowerPoint PPT Presentation
Title: Ecological Weed Management EPM13
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Ecological Weed ManagementEPM13
- Integrated Control of Musk Thistle using an
Introduced Weevil. - Richard C. McDonald, Ph.D.
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Musk Thistle - Carduus nutans L.
- Introduced into the eastern seaboard in mid-1800s
from Europe as ships ballast - Quickly spread east seeds are windborne
- Missouri - 1st detected in 1940s
- By mid-70s, major noxious weed problem
- Chemical control of all areas not feasible
- 2,4-D and Tordon were herbicides used.
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Musk Thistle Stages
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EPM of Musk Thistle
- 1973 - 1 in 10 counties in US had economic
infestations of MT. - 1 MT plant per 1.5 m reduced pasture yields by
23 - Outcompetes Natives
- Declared noxious weed-law 1981 in MO
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EPM of Musk Thistle
- Controls spraying, digging, mowing.
- Controls were not very cost effective
- Many farmers and dairymen were going broke.
- Land value decreased more than 100/acre because
of thistles.
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EPM of Musk Thistle
- Nationally, MT was causing tremendous problems
- Tordon-herbicide-contaminating water and killing
cattle - MT seemed to be out of control.
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EPM of Musk Thistle
- In Missouri, MT was costing at least 5 million
in lost forage yearly since the 60s. - Landowners/Hwy Depts - 1 million on herbicides
- Totals 6 million and 126 million/year
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EPM of Musk Thistle
- USDA researchers in Eurasia - why MT wasnt a
problem there - Insects/diseases that limited the ability of MT
to reproduce - Musk Thistle weevil
- Rhinocyllus conicus Froelich
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EPM of Musk Thistle
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EPM of Musk Thistle
- M.S. - Distribution and Impact of R. conicus in
Missouri (1982) - Determined types/amounts of controls used
- Visited 99 release sites - thistle density,
weevil density, and seed production - Impact of weevil on thistle populations over a
total of 5 to 7 year period.
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EPM of Musk Thistle
- At each site - sample EPM form
- Recorded thistle density, presence/absence of
weevil, samples of terminal and lateral
flowerheads to determine seed production
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EPM of Musk Thistle
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EPM of Musk Thistle
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EPM of Musk Thistle-Findings
- 1 million acres infested in Missouri
- 1 million in herbicides most controls were
applied incorrectly - Musk Thistle weevil caused a 70-95 reduction in
thistles with EPM - rotational grazing, pasture
management and focus on biological control - Increase establishment and efficacy of weevils
- Published Guidesheet with findings
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EPM of Musk Thistle
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EPM of Musk Thistle
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EPM of Musk Thistle
- q - level of suppression by weevil
- q new equilibrium population/prior equilibrium
position - q 109/1936 0.05
- In our study plots, data showed a 95 reduction
in thistle density with no other controls applied.
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EPM of Musk Thistle
- Graph of MT population density at initial release
site - Graph of weevil densities per head at original
release site
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EPM of Musk Thistle
- MT biocontrol program caused a 70 to 95
reduction in musk thistle density after 5-7
years. - Resulted in an annual savings of 6 to 126
million dollars in increased land value and
reduced use of herbicides, especially Tordon and
2,4-D. - Program was run on 3000/year!
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EPM of Musk Thistle
- We were able to increase collections, releases
and establishment rates for the MT flowerhead
weevil. - Sustainable suppression of thistles Missouri
does not have economic levels of thistles now. - We were able to Integrate control methods to
suppress thistles and protect weevils.
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