Managing Herbaceous Perennials in the Tahoe Basin s Sensitive Habitats

Transcription

1 Managing Herbaceous Perennials in the Tahoe Basin s Sensitive Habitats Jennifer Erskine Ogden 1, Mark J. Renz 2, Justin Norsworthy 3, Sue Donaldson 4 1 University of California, Davis, 2 University of Wisconsin-Madison, 3 New Mexico State, Las Cruces 4 University of Nevada Cooperative Extension

2 Lake Tahoe field study Small invasions of perennials in Tahoe Basin Knapweeds Toadflax Perennial Pepperweed Herbicides cannot be sprayed in sensitive areas Volunteer crews available for field work Background

3 Quantify if applying herbicide on a cut surface will: Purpose of study Effectively control plants Minimizes environmental impact Provide land managers with an effective management option in sensitive areas with large volunteer pools

4 Study Species Dalmatian toadflax (Linaria genistifolia ssp. dalmatica) Diffuse knapweed (Centaurea diffusa) Perennial pepperweed/ Tall whitetop (Lepidium latifolium)

5 Methods evaluated Klipkleen / Dip & clip (greenhouse and field) Cut and drop (greenhouse only)

6 Herbicides and rates used

7 Methods: Greenhouse study: Perennial pepperweed Dropper Dipped clipper Stage of plant: Flower bud Flowering Size of root fragment: 1-22 grams 3-66 grams Treatments used: Telar Glyphosate Cut only Untreated control

8 Results of greenhouse study

9 Percent reduction in perennial pepperweed alive belowground biomass 45 days after treatment % reduction in alive belowground biomass a a b 0 Telar Glyphosate Cut Only P<0.05

10 Percent reduction in perennial pepperweed biomass 45 Days after treatment a b 1-2 g 3-6 g P<0.001 Percent reduction in in alive root root biomass

11 5 4 Results of management methods on biomass allocation 45 days after treatment Telar Glyphosate Cut only Uncut control Grams dry weight prt alive prt dead new rts subshoots

12 Field sites 2 perennial pepperweed

13 Field sites 1 diffuse knapweed 1 Dalmatian toadflax

14 5 Replicates/treatment Untreated control Cut only Dip and clip (telar, glyphosate, transline) Backpack spray Percent cover of all species in four 1m 2 quadrats/replicate Data collected pre- treatment & 1 yr post- treatment Data collection

15 Dalmatian toadflax

16 Dalmatian toadflax results 30 Percent cover of dalmation toadflax 1 year after treatment * = sig. diff from untreated control p<0.05 adult seedling Percent cover of Dalmation toadflax * * 0 untreated cut telar glyphosate transline spray (tel)

17 Changes in cover of Dalmatian toadflax over time 60 % cover Dalmatian toadflax Cut Glyphosate Spray Telar Transline Year effect significant (p<0.001). Year*treatment effect barely significant (p=0.053 using repeated-measures ANOVA. Untreated

18 Changes in cover Dalmatian toadflax over time 60 % cover Dalmatian toadflax Cut Glyphosate Spray Telar Transline Untreated Year effect significant (p<0.001). Year*treatment effect barely significant (p=0.053) using repeated-measures ANOVA.

19 Control with glyphosate & telar

20 Changes in toadflax community composition after treatment using PCA SAMPLES Untreated Cut Telar Glyphosate Transline Spray

21 Diffuse knapweed site

22 Diffuse knapweed results 10 Percent cover of diffuse knapweed 1 year after treatment adult seedling Percent cover of diffuse knapweed * = sig. diff from untreated control p<0.05 * * Untreated Cut Telar Glyphosate Transline Spray (tran)

23 Changes in diffuse knapweed community dynamics Treatments controlled 2005 PCA diffuse knapweed 21 1 Community changes not seen using PCA: Treated plants replaced with bareground and litter Few natives to re-establish establish SAMPLES Untreated Cut Telar Glyphosate Transline Spray

24 Perennial pepperweed: What happens when it rains? 2 inches above average rainfall in October 2004 (Carson City, NV)* 1.5 inches above average rain/snow in March 2005 (Glenbrook, NV) * Yearly avg. precipitation in Carson City: 11.8

25 Percent reduction in cover from Perennial pepperweed results Percent reduction in cover of perennial pepperweed 1 year after treatment * = sig. diff from untreated control p<0.05 * * tahoe hot creek Untreated UTC cut Cut Telar Glyphosate gly spray Spray (g)(gly)

26 Changes in cover of perennial pepperweed over time 35 % Cover Perennial pepperweed Cut Glyphosate Spray Telar Untreated No significant year or year*treatment effect using repeated-measures ANOVA

27 Changes in cover of perennial pepperweed over time 35 % Cover Perennial pepperweed Cut Glyphosate Spray Telar Untreated No significant year or year*treatment effect using repeated-measures ANOVA

28 Sometimes spraying herbicide might help the target species...

29 Treatment effects on perennial pepperweed community dynamics No changes in plant community dynamics with the treatment of perennial pepperweed in sprayed or dip and clip plots Other factors (rainfall, flooding) outweighed effects of treatment

30 Conclusion data after one year of treatment...

31 Treatment reduces but does not eliminate future years growth Future management needed for seedlings/resprouts Both methods effective If drop falls off reduced control Changes in plant community dynamics seen in toadflax site with the dip and clip method. Other sites/species have the potential for similar results. Conclusions Rainfall plays significant role in establishment of plants.

32 For more information on our study please see University of Nevada Cooperative Extension Publication publications/files/nr/2006/ SP0609.pdf

33 Acknowledgements Funding: UC IPM Exotic/Invasive Pest and Disease Research program Site location/accommodations Larry Hughes, Douglas County Tahoe Basin Weed Coordinating Group South Lake Tahoe Trout Farm Alison Stanton