1. Can Herbicides Broadcasted in the Fall
Control Canada Thistle And Maintain Forb
Cover In Establishing Prairies?
Brendon J. Panke, John W. Albright,
and Mark J. Renz
University of Wisconsin-Madison
2. BackgroundBackground
• Establishment of native prairies is popular
for many reasons.
• Perennial weeds, such as Canada thistle
can severely hinder the establishment of
planted prairies.
• BMPs exist for the establishment of
prairies.
• Often, BMPs are not followed.
3.
4. Problem and ObjectivesProblem and Objectives
• Canada thistle suppression to enhance
establishment of new prairie
– Range of herbicides available for use on Canada thistle
– Some native species senesce before Canada thistle
– Some native species tolerant to herbicides
OBJECTIVES:
• Determine if herbicides applied in the fall
1. suppress Canada Thistle
2. Increase native grass and forb cover
3. Increase # of native grass and forb species
6. Horicon, WIHoricon, WI
• HISTORY: Agricultural fields acquired
• LAND PREP: Disked 2006 before seeding
• PLANTING:
– Planted in July 2006
– Wildlife planting (5 grasses + 21 forbs)
7. McFarland, WIMcFarland, WI
• HISTORY: Fallow for several years
• LAND PREP:
– 2006: gly+2,4-D summer + fall
– 2007
• gly +2,4-D summer
• Disked 2007 in fall before seeding
• PLANTING:
– Fall seeded November 2007
– Prairie restoration (61 forbs + 3 grasses)
8. Native plants present when treatedNative plants present when treated
Species Common
Achillea millefolium yarrow
Andropogon gerardii big bluestem
Arnoglossum atriplicifolium pale indian plantain
Artemisia ludoviciana prairie sage
Aster ericoides heath aster
Aster novae-angliae New England aster
Astragalus canadensis Canada milkvetch
Baptisia alba wild white indigo
Desmodium canadensis Canada tick trefoil
Echinacea purpurea purple coneflower
Elymus canadensis Canada wild rye
Euphorbia corrollata flowering spurge
Monarda fistulosa beebalm
Oenothera biennis common evening primrose
Panicum virgatum switchgrass
Potentilla arguta prairie cinquefoil
Rudbeckia hirta black-eyed susan
Solidago rigida rigid leaf goldenrod
Sorghastrum nutans indian grass
Species Common
Asclepias syriaca common milkweed
Aster ericoides heath aster
Aster novae-angliae New England aster
Elymus canadensis Canada wild rye
Euphorbia corrollata flowering spurge
Monarda fistulosa beebalm
Oenothera biennis common evening primrose
Panicum virgatum switchgrass
Rudbeckia hirta black-eyed susan
Silphium integrifolium rosinweed
Silphium terebinthinaceum prairie dock
Solidago rigida rigid leaf goldenrod
Zizia aurea golden alexander
McFarland (1 YAP)McFarland (1 YAP) Horicon (2 YAP)Horicon (2 YAP)
9. Herbicides evaluatedHerbicides evaluated
applied Fall of 2008applied Fall of 2008
Herbicide Rate used Typical Rate
2,4-D 1 pt/A 2-4 pts/a
Escort (metsulfuron) 0.3 oz/A 0.5-1.0 oz/a
Banvel (dicamba) 1 pt/A 2-4 pts/a
Milestone (aminopyralid) 1 fl oz/A 7 fl oz/a
Milestone (aminopyralid) 5 fl oz/A 7 fl oz/a
Roundup (glyphosate) 7 fl oz/A 22 fl oz/A
UTC - -
10. Canada thistle status HoriconCanada thistle status Horicon
SEPTEMBER EARLY OCTOBER
LATE OCTOBER
11. Canada thistle status McFarlandCanada thistle status McFarland
SEPTEMBER EARLY OCTOBER
LATE OCTOBER NOVEMBER
12. How did we measure success?How did we measure success?
• Decrease in cover of CT
• Increase in cover of native
plants
– Total vs Forbs vs Grasses
– Planted vs unplanted
• Increase in # of plants
– Total vs Native vs Planted
13. 6 MAT Canada Thistle Cover6 MAT Canada Thistle Cover
*
* * * * *
• No differences in CT cover among timings
14. 1 YAT Canada Thistle Cover1 YAT Canada Thistle Cover
*
****
**
• Late October was the best timing at McFarland
15. 2 YAT Canada Thistle Cover2 YAT Canada Thistle Cover
• No differences in CT cover
• CT cover reduced compared to previous years
30. ConclusionsConclusions
• Canada thistle can be suppressed with
reduced rates
– Suppression was 6 months – 1 year
– Milestone most consistent
• Native cover may be improved
– Site, tolerance of forbs likely plays a role
– Milestone showed best native forb cover
• No increase in # planted species observed
31. Management implicationsManagement implications
• Disking is not recommended as a site
prep tool for prairie establishment when
Canada thistle is present.
• Canada thistle management should be
conducted prior to planting prairie plants
• Management > 1 year after planting does
not increase planted species density.
