Wildflower establishment after herbicide applications

Mark Renz1, Mike Moechnig2, and Mary Halstvedt3 1University of Wisconsin-Madison; 2South Dakota State University; 3Dow AgroSciences

Why is this research important?

• Interest in restoring mixed forb grass prairies

• Invasive plants can reduce establishment

• BMPS recommend management prior to establishment, BUT

– Many herbicides can persist in the soil for months

– Has the potential to reduce establishment

Establishment of clover in pastures from frost seeding

Untreated area

Treated area (milestone)

Why study this?

• Tolerance of species to herbicides is highly variable and rate dependent

• Forb seed are expensive

• No data on tolerance of native forb species common to Midwestern US when applied before planting

Objectives of this study

• To determine if herbicide applications the summer before planting will reduce establishment of common forbs for mixed prairie plantings:

– Fall dormant seeding

– Spring seeding

Methods

• Conducted at Arlington WI, and Beresford, SD

• Split-plot with four replications – Planting method Main

plot

– Herbicide sub plot

• Herbicides applied in July 2009

Methods

• Forbs planted with No-till drill in rows – Fall 2008 (dormant)

–Oct. (WI) – Nov (SD) =3-4 months after treatment

– Spring 2009 – April = 9 months after treatment

• Forb density counted per row – June 2010 (1 YAT)

– October 2010 (1.5 YAT)

– July 2011 (2 YAT)

What herbicides did we spray? Active ingredients rates

(lbs ae/A) Product rate

aminopyralid 0.047 Milestone 3 fl oz/A

aminopyralid 0.11 Milestone 7 fl oz/A

aminopyralid + metsulfuron

0.11 +0.02

Chaparral 3.3 oz/A

aminopyralid + triclopyr

0.08 +0.75

Capstone 6pt/A

aminopyralid + triclopyr

0.11 +1.0

Capstone 8pt/A

aminopyralid + clopyralid

0.047 +0.21

Milestone + Transline

3 + 9 fl oz/A

clopyralid 0.21 Transline 9 fl oz/A

clopyralid 0.375 Transline 16 fl oz/A

tebuthiuron 0.4 Spike 0.5 lbs/A

What species did we evaluate?

Wisconsin South Dakota Black-eyed susan Rudbeckia hirta Black eyed susan Rudbeckia hirta

Lance leaved coreopsis Coreopsis lanceolata Lance leaved coreopsis Coreopsis lanceolata

Blanketflower Gaillardia pulchella Blanketflower Gaillardia pulchella

Wild Bergamot Monarda fistulosa Wild Bergamot Monarda fistulosa

Smooth blue aster Aster laevis New England aster Aster novae-angliae

Yellow coneflower Ratibida pinnata

Purple coneflower Echinacea purpurea Prairie coneflower Echinacea pallida

Round headed bush clover Lespedeza capitata Purple prairie clover Dalea purpurea

IL bundleflower Desmanthus illinoensis

Canada milk-vetch Astragalus canadensis

Golden alexander Zizia aurea

Analysis of plant density

• Analyzed each site and species within sites separately

• Analysis of Variance (ANOVA) for each sampling period • SAS PROC Mixed

• Means separation with LS means (p<0.05)

Species WI SD Planting Herbicide PxH

Black-eyed susan X X Varied by site Varied with time NS

Lance leaved coreopsis X X <0.01 Varied with time & site NS

Blanketflower X X <0.05 Varied with time NS

Wild Bergamot X X <0.01 Varied with time & site NS

Smooth blue aster X Varied with time NS NS

New England aster X NS NS NS

Yellow coneflower X Varied with time Varied with time NS

Purple coneflower X <0.01 NS NS

Prairie coneflower X Varied with time 0.01 0.04

R-headed bush clover X <0.01 NS NS

Purple prairie clover X <0.01 NS NS

IL bundleflower X <0.01 NS NS

Canada milk-vetch X <0.01 <0.01 NS

Golden alexander X X <0.01 Varied with time NS

Results were site and species specific

0

0.5

1

1.5

2

2.5

3

3.5

4

Pla

nts

per

met

er

fall

spring

Effect of planting date on forbs 2 YAT Wisconsin

* *

*

*

*

*

* Indicates difference between planting dates P<0.05

00.5

11.5

22.5

33.5

44.5

Pla

nts

per

met

er

Fall

Spring

Effect of planting date on forbs 2 YAT South Dakota

*

* *

*

*

* * *

* Indicates difference between planting dates P<0.05

Effect of herbicides on forbs 2 YAT Wisconsin

BE-susan LL coreopsis Y cone-flower

Plants per meter

Mile 3 fl oz/A 1.4 2.4 2.6

Mile 7 fl oz/A 1.3 2.4 2.3

Chap 3.3 oz/A 0.6* 1.9 1.5

Capstone 6pt/A 0.5* 2.1 3.2

Capstone 8pt/A 0.7* 1.5 2.5

Mile 3 + Tran 9 fl oz/A 1.2 1.8 2.2

Transline 9 fl oz/A 1.0 2.7 2.6

Transline 16 fl oz/A 0.4* 2.2 3.0

Spike 0.5 lbs/A 0.5* 0.6* 1.3

UTC 1.6 2.2 2.4

* Indicates different than the UTC p<0.05; Red lower, green higher

Prairie CFlower

BE-susan

Canada milkvetch

Bergmot G Alex

Plants per meter

Mile 3 fl oz/A 3.4* 3.1 1.5* 3.4* 0.9

Mile 7 fl oz/A 3.3* 2.8 1.3* 3.0* 0.6

Chap 3.3 oz/A 0.9 2.1 0.3 1.8 1.1

Capstone 6pt/A 2.6* 2.6 0.8 2.5 1.0

Capstone 8pt/A 3.1* 2.6 1.0 3.8* 1.3

Mile 3 + Tran 9 3.9* 3.4* 1.8* 2.9* 1.6*

Transline 9 fl oz/A 3.0* 2.5 1.0 3.1* 1.8*

Transline 16 fl oz/A 3.0* 3.4* 1.8* 3.9* 1.3

Spike 0.5 lbs/A 1.9 1.5 1.0 1.9 1.1

UTC 1.6 2.0 0.4 1.3 0.6 * Indicates different than the UTC p<0.05; Red lower, green higher

Effect of herbicides on forbs 2 YAT South Dakota

Most plots looked like this

Not all:Spike

Conclusions

• 86% forbs showed no differences or increased density from treatments when applied 3 months before planting.

– B-eyed susan sensitive to milestone, chaparral, & spike at one site

– Lance leaved coreopsis sensitive to spike

• Fall dormant or spring plantings had no effect on response to herbicides • Prairie coneflower was the one exception

• Results demonstrate: Herbicides can be used prior to planting forbs to control invasive plants